We'll be adding shear-webs top and bottom to the cage to stiffen things up, and I've used leftover alloy sheet for this which is 1.20mm gauge and about three inches wide.
In past prototypes the amount of material I've used has been way over spec for proofs of concept, and besides the inevitable switch to carbon-fibre spars will render a lot of it surplus to requirements anyway.
For technocrats amongst you, that's 4 x 12mm pop-rivets I'm using, tho' 10mm will do.
