Ok, I'm happy with the performance of 4 AA's (edit: Wired 2x parallel... the circuit cannot handle more than 3V input). The problem is I needed a new tin. A regular altoids tin would work for 3, but I couldn't find a 3-battery harness. So I went with a slightly larger one...
A little bit of wasted space, but it works:
And yeah, I'm not as thrilled with the final design, but it will work for now. It's all held in there with double-sided tape anyway, so I can upgrade when I find the perfect vessel:
Any ideas on another case???
