This is fun. You kids could do it.
1. Take a piece of washed white cloth. Stretch it over a paper upc (plastic) and secure it with a rubber band.
2. Draw designs on it with sharpie colored permanent markers.
3. While it’s still stretched over the cup, drip rubbing alcohol on the design. I used a dropper but a teaspoon would work.
4. It will cause the colors to spread. It’s really fun to see what you get.
6. After it’s dry iron it to “set” the colors.