What Fun! Foamy paint! It will give depth and texture to their art work and be loads of fun to create with.
To say nothing of loads of fun to make as well. Cheap aerosol shaving cream- not the more expensive gel kind, plus food coloring. Because of the way food coloring stains hands ( although it comes off readily in the bath), I wouldn’t recommend this as a party activity. Bathtub needs to be handy.