I found some plastic cases at Walgreens that are really cheap ($2) and just the right size for my rechargeable Ds and Cs. I get 12 Ds in one and they can't rattle or short. I just got a bunch of Cs and Ds from Amondo so I'll be making another 12 D box and a C box hopefully today. I haven't figured out how many C holes it will work out to but anything over 12 will be great.
I cut foam to fit each box. I looked around checking this and that kind of pipe to use as a die cutter that would cut holes
just the right size for each cell. Once you have the right sized diameter 6-8" lengths of pipe you just sharpen it a bit by putting a bevel on the end you want to cut with. For different sized cells I used:
- For D sized holes: Chromed 1 1/4" bathroom sink drop-tube (drain)
- For C sized holes: 3/4" ID type M copper
- For AA sized holes: 1/2" ID type M copper
- For AAA I used a slightly denser foam and a high speed drill.
Just cut the holes with a twisting motion. If you can't make it work your foam may be too soft. If you have trouble only at the bottom of the cut try putting a piece of rubber gasket material under the foam to cut into at the end. Cardboard will also work but you'll have to sharpen more often. Once you get the hang of it you'll be able to make a perfect, clean hole every time.
Once the holes are cut you may cut pieces off the foam plugs you just cut out and stick one in each hole so the cell never bottoms out.
Not everyone wants to go the hands on route but once you are confident that you can cut the right sized holes to protect your cells -- you can use any kind of container you like. I've used the same technique with Rubbermaid and Tupperware boxes with watertight lids, for example.