[Patrick]

I didn't buy the aluminum, it's just some pieces that weren't going to be used at work.
I'm not really sure where other guys get their material from, but if I was going to buy some it would be thinner and higher grade stuff than I used (mine is pretty heavy).

The motor adjustment slots are a bit tricky. I marked out where I wanted the slots, then drilled a line of 3mm holes as close together as possible, and used the dremel with a router type bit (I don't know the exact name for it) to get rid of the remaining material.
If you do one like mine or the rc monster mounts then it also holds one of the center diff bearings, so you want all of that to be as staight as possible, otherwise the center diff will sit at an angle.
If you make a mount like cart213's (I assume his is the other ST-1 you saw) it still uses the stock diff holder on both sides, so it won't have to hold the center diff bearing.