I am guessing you plan to form a L with 2 pieces. You can use the thinner 1/8 to bolt thru, but I would make the motor plate out of thicker al and drill/tap it so that you can bolt the L foot to it. That would require the use of countersunk screws as the heads would be on the chassis, and you want the lower plate flush. I would just buy so L angle al, that is what I used on the GTP...