You have 3 choices here:

A monocoque? (spelling please):
Literally meaning 1 shell in old french. Basically the posh term to mounting everything to the armour and base panels. Used often in feathers to improve armour.

A chassis. A frame and supporting structure used to hold everything to and to hold the armour in place. Weightly but has slightly more reliability.

or

a combination of the above.

If youre thinking of using polycarbonate for a shell, I recommend metal panels over the edges. you only have to see terrorhurtzs S5 battle for an answer...

Oh and Woody: Why would he post a heavyweight construction in the featherweight section???