One thing I use and sell art-wise are my greeting cards. My supply was running low so I got the assembly line going: cut up the painting, rubber cement onto the blank cards, leave under a brick for a while and then draw some more on the image and outline. It’s very relaxing.
When I was young and living in the city, I made a lot of greeting cards. One of my proudest moments was when I brought them to an open buying day at Henri Bendel. The buyer liked them and bought them all from me for something like two or three bucks each. This was one that I must have particularly liked and saved. Found it when cleaning up my sister’s apartment. I believe it is all colored markers probably watered down in places.