Brian, what thickness of aluminum are you using for your battery holders? I may try your technique with some 1/8" thick polycarbonate, and then use heat (torch) to soften the plastic enough to be able to bend the tabs.

I'm using 1/16" thick 6061-T6. I was going to look at using plexi/ploycarb, but wasn't sure how it would stand up to track (read: crash) abuse. I was afraid it would crack with the sudden stresses.

It'll be interesting to see how that works. I'm just too chicken when it comes to protecting my lipos.

BTW: I was playing with some 1/16" polycarb/lexan/plexi and a heatgun works very well to soften it enough to bend. Gotta be careful though, because it seems to heat very quickly; one minute it's too stiff to bend, then a second later it's all but a puddle. Funny how that works...