I'm going to be making my own truggy chassis for my T-maxx and would like to know if you guys have any input on which would be a preferred metal for this job. I plan on cutting the chassis much like a hellfire's chassis. 18" long with attached skids and 8" that narrows to 6" or so wide.

7475-O at .25" (6.35mm)
6061 at .125" (3.175mm), .16"(4.064mm) , .1875"(4.7625mm) and also .25"(6.35mm)
7075 at .25"(6.35mm)

Please help me on this... i'm stumped on which metal to choose from! Thank you!