Note, my method is best for pin marks on curved surfaces or shallow ones on level surfaces. Deeper ones call for a slightly different method (still requires repainting though). Before I had a punch and die tool (this is my preferred method now), I would mark the edges of the pin mark with a permanent marker. I would then apply a little baking soda within the pin mark if it was sunken. Over this a drop of cyano-acrylate thin glue in the CENTER of the pin mark and I would watch it spread out and harden rather quickly. Sometimes a second drop was needed. Last, as Moon Puppy wrote, sand, sand, and sand until the permanent marker around the pin mark is gone. This indicates the pin mark is now level and probably invisible.
If the pin mark is proud, a curved blade on curves, or a chisel blade on level surfaces. I use the permanent marker around the pin mark to let me know if I am gouging. When I see scratches, I switch to sandpaper (different grits) which I 'super glued' to a pencil's eraser. Twirling the pencil acts like a mini sanding wheel and I then complete the pin mark removal.
Really old school methods. Surely, some of you are old enough to remember those tricks? OK, I won't call you Shirley.
Regards,