And then there were six

Most of my time on Zandrevel lately has been soldering batteries together and building a pack to put them in. Here's the negative side of the batteries all soldered together. Note that this is only 2x5 (I'm waiting on two more sets of batteries to get here).

Here's the front. I reused some of the old octopus connectors to save some cash.

And here's the other pack built up to 2x6. For scale, here's a ruler laying across the batteries:

I'm still looking for a suitable foam to put between the batteries and the PVC that's stiff enough that it won't settle over time. I'm thinking about that hard black shipping foam that we use at work. I found a great foam at Home Depot, but they don't sell it... it's for display only. WTF?