thumb prints made into Christmas lights. Easy craft to do with the kids. To enhance this, I might extend the strand each year, so by the time they are older, you have a long string of thumb print lights.
Using only your fingers and an ink pad, you can create amazing miniature works of art. Children AND adults enjoy making thumbprint art - I know because I couldn't resist making these with my daughter. I can't take credit for the idea of thumbprint.