Well if I do go down the Nyloc nut route with the wheels, what'd be the best way of getting the nut into the HDPE? And when I measured the drill axle, I think it needs to be an M8 or M10 nut. Would this happen to be alright?

Also, for clarification, I managed to get the controller that Maxamuslead put up. I'll just use the other controller for the weapon and give my friend something to use if we're both out there. :P