Contact lens case as watercolor tray or tooth holder
Tracy has sent so many great hacks over the years, but this one stands out:
We've used old eye contact cases to make homemade watercolors in (just be sure to let them air dry before screwing cap on again or you may end up with mold problems).
Also, we've used them to keep teeth in. [Presumably while they are awaiting pickup by the Tooth Fairy. -- Ed.] When I was younger we used old 35mm cases, however in the age of digital cameras film canisters are just not abundant anymore.
Tracy (or anyone) -- I forgot to ask you how to make homemade watercolors. Care to explain in the comments?