Soap bubble paint!
So fun and easy. The children do EVERYTHING themselves, even the mixing process (together with an adult).
Mix a good dose of paint with a little water - maybe add three or four sprays of zalo and test it out. The children blow so that there are lots of bubbles and put these on the sheet. When you pick up the sheet, there will be colors on it as long as there is enough paint in the mixture.
Good luck, the kids loved it