I don't have any pictures to share of this but it works. There is a product called 'Durham's water putty'
It mixes like Portland cement, fine yellowish/tan powder, a little water at a time until its the consistency of thin mud.
You can patch near anything with this, but its mostly for wood. Make it, dip a toothbrush into and flick it on. Sounds like an old amateur method, but the results are workable. It takes awhile to dry if it goes on thick though if put on thin it will dry fast. You can dye it with water colors or acryls. It has a decent sticking property and it can be removed unless you give it a dull cote spay when dry.
Used to do this years ago- amateurish effect, but its quick and cheap. And sometimes thats best! best thing is if you don't like it, you can get it off.
You can buy it in a cylindrical oatmeal sized can for about 8 bucks. Lasts forever. Just don't eat it