Today my student teacher made some shaving cream prints.
She put shaving cream into a shallow tray and then poured in vegetable dye. They used combs made from stiff cardboard to make patterns in the foam. They then gently placed A4 paper over the top and pressed down carefully. They peeled it off and allowed it to dry. When dried it was laminated and the patterns, if they didn't smear them all so that they made a big brown/green mess ( which some did) turned out really well.