Simple battery holder. Holds 12 18XXX, 7 14XXX or AA, 4 20XXX, 6 10XXX or AAA, 1 21XXX, and 2 26XXX batteries. Nothing fancy, just functional for people who have a variety of battery sizes rolling around their table or desk.

It's a simple design that met my needs at the time, and it would be simple to design your own or modify this to fit your needs.