You don't need to use a Powerade bottle, anything with a lid large enough to fit a quarter is good enough, this is just what I had on me at the time.
Step 1: Materials and Creation
1) Empty (Powerade) Bottle with lid
What you do is trace a rectangular box on the lid of the bottle, and use your dremel to cut it out.
Sand the inside of the cut if you like.
Step 2: Decorate?