And there's more than a multitude of stencils available in all kinds of designs and various ways to create your own. Those shown are thin plastic and I've added painter's tape around to edges to increase the area to hold them in place when they are being used. They are still easily washable.
By putting the basic supplies to use with the stencils and gelli plate you can create all sorts of backgrounds and entertain yourself for many hours. Work near a sink if possible and have the baby wipes close at hand.