hey and welcome its late so ill give a rough fast reply lol

drills are way to heavy for an ant weight not to mention too big for an ant weight -drills are what most people use in feather weights (13.6kg robots)-also antweights have to fit in a 4 by 4 inch square to be allowed to fight- or at least they used to have to - im not an antweight guy so im not all that sure.

and yes the design looks alright for an antweight, bu not to push you into anything but if your wanting a metal shell n all might be hard to get all that in the weight of an ant weight, you could be better off making a kilobot instead- theres a thread about kilobots just below/above this one you should take a look.