In need of a portable power supply, [Alastair] threw some batteries into an Altoids tin. The problem was he didn’t have a holder for these size A23 cells. Inspiration struck and he realized the blister pack they came in fits them snuggly and just needs some conductors to complete the circuit. He pulled some battery contacts from a broken CD player. Using foam-based double-stick tape he added some spring to the contacts and came up with a perfectly sized holder that works wonderfully.

We’ve tried making battery packs by wrapping the entire thing in clods of duct tape. This looks like it works a lot better and there’s still room to fit the batteries and a switch inside of this minty enclosure.