My kids paint nearly every day. We have used all sorts of things to hold the paint: jars, paper plate, glass plates, the floor… but none work as well as a cardboard egg carton. We get the brown eggs from the store and they come in the cardboard containers. The great thing about those is that you can pour paint right into each dip, making it less likely to spill or tip over and it also has (atleast ours do) a perfect middle with holes that fit paintbrush handles!
Then to clean up, just close up the container and toss in trash.
I hope this helps someone out there that may not have thought about it. Don’t forget to pin!