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1/18 scale Flettner Fl-282V21 Kolibri scratchbuild

1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

CHAPTER X - Parallel build challenge? Accepted

When I started this project almost two years ago, I had in mind to also present the “cutaway” model kit version step-by-step WIP, as soon as the “full fuselage” model kit building would have been completed. Actually, both versions already built multiple times as commision work for collectors (for example click HERE to see both versions frames placed side-by-side, while painting process) and I only had to write the text and later attach the pictures shot during assembling & painting process.


Considering that over 130+ model kits of both versions sold since Anyuta 3D produced the very first 3D printed V6 version kit under 1/18 scale on early 2014 and due to the fact that the V21 cutaway version became quite popular the last few days, I am now thinking to change a little the basic plan and let the cutaway version step-by-step building edit into the full fuselage version WIP and present them both as a parallel project into a single forum thread.

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As you all understand, the “cutaway” version is actually based on the previously released “full fuselage” model kit, but more than 50% of parts should be CAD designed from the start in order to achieve best results. Although both versions are accurate miniatures of the Kolibri V21 helicopter under 1/18 scale, each one follows different assembling methodology. During the CAD phase, the individual kit parts designed in such way to be as easy as possible for the average modeler to build the model. To do so, the total number of tiny parts reduced (as possible) and different components combined into one part only. IMHO, building something from scratch is not so difficult - after all, we all tried some scratch once in a while. On the other hand, designing a helicopter model from scratch, exploding it into 60+ parts and make each one of them possible to get re-assembled & combined all together in order to create a miniature, is not a piece-of-cake. Speaking of a “cutaway”, the design difficulty factor gets multiplied.

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If you download the 102-page "full fuselage" and the 67-page "cutaway" PDF formated building instructions manuals, you'll notice the building process differencies on the first pages. Both versions have exact same dimensions when models fully built, but each assembling process differs a little. For example, as shown into following picture:

  • The "full fuselage" version kit is equiped with four full-length rotor blades (measuring approx 28 cm long each), but the "cutaway" version has the short / chopped rotor blade parts (marked into red ellipse), to simulate the Kolibri found by British Army and now preserved by Midland Air Museum, in cutaway condition.
  • The "full fuselage" version's main tubular frame is a little shorter (marked into red circle in following picture) than the normal-length “cutaway’ version's tubular frame. This is because the "full fuselage" version's rear fuselage cover part (which simulates the doped fabric covering over the steel & wooden frame and moreover has the vertical stabilizer attached on) should be dragged along the miniature's wooden frame, until reached down on the transmission pivots. So, as you understand, few milimeters of empty space are needed to ensure the appropriate contact.
  • The "full fuselage" version's main tubular frame is equiped with a "sleeve" (marked into purple ellipse in following picture) over the front tubular frame. Actually this is a bracket made of wood to support avionics & radio either side of the pilot at cockpit area. This "sleeve" part as well as some others like eg batteries, avionics & radio, 25 litres cylindrical fuel tanks mounted externally on both sides of the pilot, seat cushions etc are also missing from the "cutaway" version.
  • The undercarriage support (marked into blue ellipse in following picture) is different on each version. Although both versions will show the same on this undercarriage support area when models are buit, the “full fuselage” version's main tubular frame is missing this part, since it is already attached on the rear fuselage cover part.

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  • The vertical stabilizer of the “cutaway” version kit is offered as a separate part, which should be glued on the wooden frame. On the other hand, on “full fuselage” version kit, the vertical stabilizer is already attached on rear fuselage cover and offered as combined items.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

After studing the available reference (few hundreds of pics, blueprints, slides & negatives, videos, technical data and original Luftwaffe's text documents) kindly offered from a variety of sources such as Deutsches museum flugwerft schleißheim, Hubschraubermuseum Bückeburg, Midland air museum, a fellow modeler from Germany whose grandfather was a worker in the Anton Flettner Flugzeugbau GmbH factory at the time when the helicopters manufactured, Mr. Steve Coates author of the "Helicopters of the Third Reich" book and ofcourse Mr. Google (modeler's best friend), the already existing CAD digital file converted to Kolibri cutaway. Now, the model is ready to be forwarded to the 3D replicator and become an actual physical object under 1/18 scale, within short time.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Approx 50% of the components are copied & pasted from the already existing full fuselage version and (lucky me) I did not had to design everything from the start. For example, the complex of intermeshing rotor gearbox, the 7-cylinders radial engine, the 24° angled rotor heads etc. On the other hand, all the “wooden frame” parts such as the vertical stabilizer, the rudder fin, the horizontial elevator fins and rear fuselage frame details, were CAD designed from the start. Ofcourse, the cutaway version was also built with all included truss-type welded tubes and drive shaft rods with universal joints attached on frame. IMHO, that was mostly preferred because all basic parts should be accurately pre-installed in place without any glue, putty, sanding etc.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

After digitally building the Fl-282 Kolibri cutaway 3D model using only mouse clicks, I saved it as an STL - STereoLithography format binary file and forward it on the 3D replicator to start generating the individual parts of the actual scale model. Once again, I used best available tools & plastic material and asked from Shapeways digital fabrication lab (equipped with a high-precision & high-cost “ProJet HD 3000” machine for creating custom made-to-order products), to 3D print it. The 1/18 scale Fl-282 V21 Kolibri “cutaway” model kit consists of more than 40 different 3D printed parts made of matte translucent plastic material - in fact, the kit parts are quite more, but smaller in size are interconnected on same sprue frame which is counted as one part. Kit was CAD designed and 3D produced in such way to simplify assembling process while maintaining necessary details required by the scale size. Following the instructions described into the 67-page ultra-detailed “1/18 Fl-282 V21 cutaway kit building instructions” manual (which can be found HERE as a PDF format downloadable file), the assembling process becomes easy.

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When printing is finished, the model parts are removed from the tray and placed into an oven that melts away the wax support material. Next, the models are placed into an a ultrasonic oil bath to remove any remaining wax residues, and then a ultrasonic water bath to remove any oil on the model. Final inspection and dry by hand follows for every single model part. Although the ProJet HD 3000 prints in high resolution (16 microns per layer) and can easily produce high detailed parts as small as 0.1 mm, it is better to avoid printing such small parts because they could easily get lost while washed into ultrasonic bath later, for wax residues removing. Each complete model kit takes about 5 to 7 days to get produced after order due to increased workload for 3D printed manufacturing demand in Shapeways factory.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

As soon as 3D printing process completed, the produced parts were cleaned & checked for broken parts or imperfections by Shapeways 3D printing lab specialized personnel. Later, everything carefully packed and shipped to my home address using UPS 24hrs delivery service. Once again, I was happy to hold my own custom 3D printed model kit, CAD designed with my laptop and later converted to an actual physical object, under my preferable 1/18 scale.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Some additional parts unrelated to the helicopter structure, also 3D printed to be used later as part of a diorama scene. For example few 1/18 scale 20 litres fuel canisters, a couple of 1/18 scale 200 litres fuel drums as used by Wehrmacht, Luftwaffe & Kriegsmarine during WWII with “Kraftstoff 200L Feuergefährlich Luftwaffe” and “Kraftstoff 20 L Feuergefährlich 1941” inscriptions engraved or embossed on side, a 1/18 scale fuel hand pump and one 1/18 scale wooden 3-steps ladder as used by Luftwaffe WWII ground crews and technician personnel for ground vehicle & aircraft maintenance procedures.


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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Rotary hand pump used by techical crews & maintenance personnel to transfer fuel from the 55 gallons drums to aircraft & armoured vehicles fuel tanks or into the 20 lt fuel canisters (both drums & canisters are available for sale at Anyuta 3D products catalogue). This type of manual fuel pump used by Luftwaffe & Wehrmacht during WWII. The rotary hand pump kit contains all necessary parts for assembling one fuel hand pump under 1/18 scale. Any extra diorama accessories (hose, 55 gallons fuel drum etc) are not included and should be purchased separately.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Although 3D printed models do not differ so much from ordinary kits, the plastic material may cause surprises. Some of the kit parts may feel a little greasy and appeat slight traces of oil on their surface. As I've already described into previous pages, it is absolutely normal. After the 3D printing process was finished and the kit parts been removed from the printer tray to be washed into an ultrasonic oil bath and later an ultrasonic water bath, some oil traces escaped the clean inspection and dry by hand procedure. Parts can be easily cleaned by following one of the following methods:

  • By washing parts with water (NEVER apply water hotter than 50º C / 125º F or you'll be really sorry) & dishwasher soap and brush gently with an old soft toothbrush. Keep in mind that items are only 0.3mm to 0.5mm thin and they are very fragile. Therefore, being very carefull while washing the parts is a necessary.
  • By sinking everything into a plastic bowl filled with White Spirit and leave it there for few seconds or a couple of minutes (max) to wash oil traces. In the end the the kit won’t feel greasy anymore and show an almost complete white colour. Never use anything more "aggresive" than White Spirit. Also, AVOID stove cleaning spray and acetone nail polish remover products - both clean oil & wax but also dissolve the plastic leading to breakage and failure.
  • By using hydrosonic cleaning machine (IMHO, is the best alternative), filled with water & dishwasher soap and repeat procedure if needed. Meanwhile the water will turn cloudy - that’s the wax.

It is of utmost importance that the model parts are properly degreased - otherwise the paint will not stick. Small remainders can be removed with a swab or toothpick. For my own 1/18 scale Kolibri cutaway model kit, I decided (since I do not have a hydrosonic cleaning machine) to wash slight oil traces on parts by sinking everything into a 2 litres plastic bowl filled with White Spirit and leave it there for a couple of minutes. Shortly after all kit parts enjoyed their bath into a White Spirit filled bowl, they were washed with liquid soap & warm water, placed on soft paper towels and allowed to dry.


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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

After all kit parts washed in White Spirit & water to clean the oil traces, every section of the model has been repeatedly dry fit tested to ensure that all individual parts could be later combined together as an overall built model. When looked OK to me, each part sprayed over with an undercoat mixture of 80% Life Color LC02 Matt Black and 20% Life Color LC37 Matt Burnt Umber acrylic, to prepare the surfaces for the basic paint which about to follow. Later, a very thin coat of Life Color UA503 Light Blue acrylic paint layer applied, very diluted with Life Color’s acrylic thinner in a 30% paint to 70% thinner ratio. The darkest recesses sprayed first, gradually working my way up the frame, keeping to the lighter areas on central parts of each tubular part. Same pattern maintained throughout the entire painting process to preserve continuity with the light source and subsequent spraying sessions continued to utilize very thin Life Color UA503 Light Blue acrylic paint layers as a base to varying degrees because it is the source of the light colour.


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The tubular frame got gradually lighten with each successive layer as the painting process continued, so the second layer of paint as the medium layer of the base coat, is based upon a less diluted 50% paint to 50% thinner ratio. Then, I added just a few drops of Life Color LC01 Matt White FS37925 acrylic paint into the mixture to lighten up this stage of paint application, being very careful to always follow the established gradation pattern, untill contrast between light and dark started to become apparent.


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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

CHAPTER XI - Assembling individual parts

As soon as most individual 3D printed parts on both “full fuselage” & “cutaway” scale model kit versions were already painted & weathered, everything should be combined and assembled as an overall built miniature. Having already installed the rudder fin and the two horizontial elevator fins on the “full fuselage” version model’s tail, the gear box unit was next. Following instructions described into the building manual (click HERE for the PDF formated file) through pages 33 to 37, all the four pins on gearbox unit should be simultaneously aligned onto the upper frame’s slots and same time linked downwards with engine’s transmission shaft, as shown on following pictures.

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Here is a detailed view of the correctly installed gearbox unit as seen underneath the fuselage cover. Notice that the forementioned gearbox unit is linked (marked with red circle) with previously assembled engine’s transmission through a shaft coupling.

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This is how the assembled block of rotary engine, transmission unit, cooling twin blade propeler fan, drive shaft & upper gearbox unit should look like when correctly fit into each other. Notice that tubular frame is not visible here for better example view.

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Both “full fuselage” & “cutaway” scale model kit versions are equiped with fixed non-retractable tricycle type undercarriage with a steerable nose. The tubular shaped struts & the central supporting section anchoring points aligned on proper U-shaped slots found on the lower fuselage area. Following instructions described into the building manual, the upper & lower anchoring points on each tubular landing gear strut end should be simultaneously aligned onto the tube frame’s U-shaped slot (marked with red arrows). Successful assembly of main landing gear section will positively affect process to follow - a side tilted helicopter model, would look completely unreal.

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This is how the fixed non-retractable tricycle type undercarriage frame should look like when the parts correctly installed on the fuselage frame. Everything secured in place with a drop of cyanoacrylate super glue.

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To add some weathered look on fuselage areas (doped fabric covering over the steel & wooden frame on real helicopter) and replicate parts like being dirty, dusty or sunfaded, I appplied different shades of dark brownish pigment powder, trying to blend them nicely to look artistically accepted and create 3D-alike effects on flat surfaces. The results on model may not look so “strictly realistic” comparing to the real world objects, but IMHO scale modeling has to balance between realism factor and artistic expression. I admit that adding (extensively in some specific areas) pigment powder, may not accurately replicate the reality, but it looks artistically attractive and becomes easily accepted by visual subconscious.

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The main advantage of the pigment powder shades is that the already painted scale model gets some nice weathering / lighting effect tones. On the other hand, the big disadvantage is that once the pigment powder settles on the model’s surface, it should not be touched to avoid smudging. To overcome this problem, modelers usually secure the pigment in place by carefully soaking the model surface with modeling fixer. However, even after applying modeling fixer, it is not absolutely safe to touch the model.

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I tried a different approach and used Winsor & Newton’s fixative for charcoal & pastels (instead of modeling fixer) over pigments. Although similar, the Winsor & Newton’s fixative is different from the modeling fixer. The Winsor & Newton’s fixative solution (available in 75ml and 500ml bottles) provides protection of charcoal, pencil, pastel & chalk drawings - it is mostly used by painters & pastel artists to seal the final result of their work. Although the model paint gets glossy after Winsor & Newton’s fixative applying, the good news is that model can be sprayed over with final matte coat after securing pigments with Winsor & Newton’s fixative, without leaving disastrous spots or milky stains on model (as usually happens when applying matte coat over modeling fixer-sealed pigments).

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Once the Winsor & Newton’s fixative dried, the (glossy) outcome had tonality differences because pigments applied earlier and looked like been faded by the sun, fouled by dust and stained by fuel & oil. As previously mentioned, the glossy look is not actually a problem, since the model can be sprayed over with final matte coat later, while keeping all the pigment shades.

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The wheels attached on undercarriage, according instructions described into the building manual. The U-shaped nose wheel supporting fork, pinned into the shock absorber slot while making sure that axes are aligned, as shown in following picture. Notice that nose wheel is tilted accordingly to the rudder fin (which is already installed) as previously explained.

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The twin 25 litres cylindrical fuel tanks (mounted externally on both sides of the pilot seat), attached on frame by plugging pins into proper slots as shown on the following pictures & secured in place with cyanoacrylate super glue. Since these cylindrical fuel tanks are made hollow, the sealing caps can be removed if building a refueling diorama scene. Notice the details marked into the red circles - this is how the cylindrical external fuel tanks should look like when correctly mounted externally on both sides of the cockpit area framework.

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Here is how a semi-built “full fuselage” scale model kit version looks like as seen underneath, after few of the kit parts installed. More parts such as the side & lower fuselage door panels, the rudder pedals & control levers in cockpit area, the instruments panel, the rotor heads & blades etc, will be attached on main frame later.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

CHAPTER XII - Concrete apron display base construction

When I started this Kolibri project for a collector located in Kiel, Germany and later built more identical helicopters for other customers and my own collection at home too, I was concerned about a proper display option, on which the model would be placed. My goal is to build up a simple diorama scene, which looks like a “maintenance & refueling area” on a forwarded airfield. From an artistic point of view, a “maintenance & refueling area” scene might possibly dictate everything to be into a state of complete engine oil ‘n’ grease messiness. My goal is to keep the Kolibri helicopter as protagonist into the scene, while filling the empty space with few “maintenance & refueling area” related items, to maintain a visual balance. What I am actually trying to present here, is an intentional setup to show scale model’s details through opened maintenance panels, opened hatches, removed engine unit etc without extreme diorama action, nothing that could possibly distract viewer’s attention from the Kolibri helicopter which is always the main protagonist of the story. Any other item should be standing as an uninvolved walkon to simply complete the directorial picture.

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While scale model painting was underway, I thought as good idea to place the Kolibri helicopter scene on a “grass airfield” area. My opinion had been probably shaped (aka influenced) by viewing WWII era pictures, where the Flettner Fl-282 V21 Kolibris were stationed on the fresh green grass. Unfortunatelly, the problem that would arise from such a choice, is that the (already painted green) helicopter would be visually lost into this greenish backround. Due this reason, the idea of placing the Kolibri model on grass abandoned and the idea of a concrete covered airfield apron area (with just a few short grass sprouted between concrete slabs) where pre-flight activities were done, seemed much better. The scene would require at least a 450 x 350mm display base, considering that helicopter measures approx 357mm long and 138mm wide, without counting the rotor blades with disc diameter approx 700mm each.

Those who have read my previously uploaded projects, might remember that I prefer using plaster powder to build the section that recreates the ground, especially if it is asphalt. However, the 450 x 350mm dimensions of the scene dictate plaster quantity more (and therefore heavier) than usual and for this reason I chose to use another material, because the goal was to build a airfield display base instead of weightlifting equipment for champs. For this reason, I decided to follow a different way, by replicating concrete covered airfield apron with cork sheet. I purchased two 500 x 500mm sized & 4mm thick sheets of cork from my local hobby shop, which I cut & shaped around with my Black & Decker 400W / 3000spm jigsaw. The basic idea, is to build an approx 8mm thick & flat surface which protrudes above the polished wood display base, on which short vegetation (grew between the concrete slabs) and diorama accessories (such as maintenance tools, fuel canisters etc), will be added later.

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As soon as the 4mm thick sheets of cork identically cut into shape, sandwitch glued and the concrete plaques were lined, I used my airbrush to paint it. As I usually like to do, three different acrylic paint layers were applied on the concrete apron surface. First, mat black colour covered the area and then lighter greyish and earth layers applied, while airbrushing in almost zero degrees angle, to let the darker areas between the concrete plaques remain naturally dark.

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The concrete apron surface was paint with different greyish & earth tones and as soon as the acrylic colours dried, I tried some drybrushing on selected spots using sand tones. Concrete areas on which the oil drums, the fuel canisters, the under maintenance radial engine etc will be placed later (probably resulting oil & fuel stains on ground), painted differently with more yellowish shades to replicate sawdust spread to absorb leaked oil & fuel. As for the vegetation that grew between the concrete slabs, I used some Heki static grass, secured in place with water based white glue for wood which becomes transparent when it dries. When it looked OK to me, I sprayed over with Humbrol enamel matte coat, to seal the paint & vegetation result so far and left it overnight to dry.

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Meanwhile, some of the earlier described 3D printed items (unrelated to the helicopter structure) such as few 1/18 scale 20 litres fuel canisters, one of these 1/18 scale 55 gallons oil drums and one of these 1/18 scale 200 litres fuel drums as used by Wehrmacht, Luftwaffe & Kriegsmarine during WWII with “Kraftstoff 200L Feuergefährlich Luftwaffe” & “Kraftstoff 20L Feuergefährlich 1941” inscriptions engraved or embossed on side, also got some paint, dirt & weather effects.

All the above mentioned diorama accessories are listed into Anyuta 3D products catalog and available for sale under various scales and sizes.

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The previously mentioned 1/18 scale 200 litres fuel drum received a basic layer of Life Color UA505 RLM 79 Sandgelb II / Sand Gold II acrylic paint and the 1/18 scale 55 gallons oil drum painted with Life Color UA504 RLM 02 Grau / Grey acrylic paint and allowed to dry overnight.

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Once the acrylic base coat has cured, both drums got some weathering, paint scratches and rusty chipping effects while using the sponge technique to give visual interest to the base colour. To achieve best results, I did use a fine textured sponge like those used for packing of electrical items. Fresh rust marks also added in some selected points, with some of the Life Color UA704 Rust Light Shadow 2 acrylic. Using a fine tipped brush, the Light Rust Brown & Dark Rust oil paints by 502 Abteilung & AK Interactive series painted in vertical lines from various chips and scratches added earlier. Once the oil paints had been allowed to dry for a short while, a brush dampered in White Spirit used to blend and soften these streaks for a more subtle effect and obtain visible signs of wear & oxidation.

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1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Good to see you back. Looking fantastic also :notworthy :notworthy :notworthy :notworthy :notworthy :notworthy :notworthy :notworthy (y) (y) (y) (y) (y) (y) (y) (y) (y) (y)
James
 
1/18 scale Flettner Fl-282 V21 Kolibri scratchbuil

Excellent work as always and thanks for the painting tips (y) (y) (y)

Cheers, Christian B)
 
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