If you ever had an issue finding a battery that was wandering inside a backpack, this may solve your issues.

Fits original FMC bag (although I will make 2 battery version to accomodate original FMC kit).

Also, this will help to store batteries in a more organized and protected way.

Printed with 0,3 mm or 0,2 layer height, 15% infill. No supports required. Split it into separate components and print flat.

Use CA glue to assemble it. Apply self adhesive velcro tape to secure it inside backpack/photo bag.