You might find the perfect art/rainbow party craft or activity here :) 36 Beautiful and Engaging Rainbow Activities for all ages: Babies, Toddlers, Preschoolers and even Older Kids! From Fun at Home with Kids
Make your own pumpkin puffy paint- this paint has such a FUN texture & dries PUFFY! Perfect for creating puffy touch and feel pumpkin art. A fun activity for Fall- hey this could be modified for any puffy paint.
Fun and easy DIY paintbrushes that get kids creating! Use with different "textures" of paint for even more possibilities. These are fun for every day painting or would make a great activity for a kids art themed party.