Deodorants that have a roller ball at the top are useful for craft projects. Fill them with paint and let the kids use them for simple and clean painting projects. You'll feel virtuous, too, by reusing and recycling those old deodorant bottles. Keep the cap; if you refill the bottle with a liquid, the cap will keep it from drying out. It's not hard to empty and clean the bottle to get it ready for reuse.
Stand over the sink and pry out the ball with either a dull knife, flat screwdriver or metal nail file. Don't stretch the sides of the bottle too much, and watch that the ball does not fly out and hit you in the face.
Dump any liquid that may be inside the bottle into the sink.
Run some hot water into the sink and put some washing up liquid into it.
Immerse the ball and the bottle into the hot soapy water and wash thoroughly. You can use a bottle brush to get into the bottle more easily. A flannel should do the trick on the ball.
Rinse all the soap off the ball and out of the bottle.
Lay the ball and bottle on a towel until completely dry.
Once the bottle is dry, you can fill it with tempera paint and pop the ball back into the top.
Don't let the kids do this; adults should be the ones using the knife, nail file or screwdriver to pop out the roller ball.