WJ and I did build Project One. No armor except some small bits of recycled 10mm pig-feeding trough HDPE on the steel spaceframe.
After that team Warlock did Project 2:Hex'em bolt on compound armor plates- PC over HDPE ,

My assistance on Gravity ,sturdy steel frame with light PC armor, and Tough As Nails- still using the original Hardox monocoque armor/frame/weapon.

Then with team RCC.
Hannibal , bolted ali monocoque.
Obsidian. From flimsy bolted 1mm ti/ 4mm Carbonfiber to semi monocoque 20-30mm HDPE

The rebuild of Mantis -with a welded shell Hardox/Stainless steel bolted on the original double chassis-

Bullfrog 2012, a monocoque Hardox shell.

I guess my 12 years of roboteering gave me a clue.

Concidering Bigger Brother. That was a welded mild steel shell on top of a double mild steel box section frame.
I was there when it got resurrected from a pile of mobile scrap steel armor to a combat ready robot after the beating it recieved of Hypnodisk. Anglegrinding, sledgehammering and welding. No rocket science, no expensive tools nor special skills. Just reparing.

And another point. The only real damage Storm II recieved in series 7, the ripped off front armor panel. Mild steel box section weld frame failure. The Ti plate was only scratched.