I'm pretty sure it's mild steel, although I can flip it over fairly easy by myself. I'm not sure what "heavy" is for a chassis though. It's sounding more and more like it'll be hard to move.
Heavy is a relative term when it comes to these chassis. The mode of thought is, take a certain piece is chassis and throw it in the air before you weld it on. If it falls back to the ground, it's too heavy!!
