I don’t like to waste things. That includes paint. Anytime I finish a project and have left over paint, I grab a blank piece of canvas or paper and use up all the extra on the paper. Most of the time I don’t have enough to paint the entire piece, so I let it dry and put it away until I have more left over paint. Eventually, I wind up with pieces like this:

Here is one I did on a piece of stretched canvas that had somehow acquired a stain. Once I piled several swathes of paint on the canvas, the stain was forgotten.