After trying a bunch of different ways to keep my test tubes from rolling around, especially when keeping one inside a plain plastic case or out world, I finally found a very simple solution that works well.
Simply cut some squares from a piece of plastic similar to the plastic that those Sterlite containers are made from, and drill a test tube sized hole in the center. Now your test tubes won't roll around, and they are tilted ever so slightly to keep any air bubbles in the water chamber at the end instead of the cotton side where it can cause it to dry out.
I think I made way more than I could ever possibly use. 
