don't know if you wanna know this, but you said you were building them to make them durable, so...... That blue chassis is a weak link. If you've got all the parts for it, it's made for four batteries, but even with two mine got bent to all hell. It's a pretty setup, but there simply isn't enough material to hold the weight of the batteries hanging on the side. I learned that the hard way so you don't have to! I used mine with dual evx's and dual 970's, it looked good till it bent. I was going to copy the top plate and "double it up" but never got around to it. Just an fyi. -Harold p.s.- a link to a durable blue chassis!
http://www.eastendmachining.com/emaxxchassis.html