Empty glue bottles can cleaned out and filled with paint. This makes it easy for little hands to squeeze out only a small amounts of paint.
A clean small butter containers can be used for paint tubs. This is an easy way to keep paint contained when using a brush.
And this is a good way for storing yarn. Just cut a small slit or hole in the top of a tennis ball container or Pringles container and thread yarn through. Little ones can pull out just what they need easily.