My boys love to paint and ask to do it often. The other day we pulled out all the colors of the rainbow and they painted for a good chunk of the day. We found these little birdhouses for a dollar at a craft store and decided that instead of just painting on paper, they would paint on poster board to hang on their walls when dry.
There are so many things that can be painted on! Craft stores have so many cheap wood projects that can be painted into a masterpiece by your kids. We have found masks, little boxes, pieces of wood that you can paint and hang up, even little cars, animals and toys. You may even only need to take a few steps just to find something to paint around your house. You can paint puppets or designs on wooden spoons or even go outside and find some flat rocks to paint on and turn into magnets or paper weights. You can even recycle boxes and containers and turn them into something fun (we did this once and made a giant robot). Most of the time we use kids paints or acrylic paints. Go out and find something fun to paint and create!