Lock Nut with M3x10mm countersunk

I changed the lock nut (plug connecting the main body and lid) to accept a M3x10mm countersunk screw to avoid having to use glue or the risk the lock nut slipping out. This replaces the M3x8mm countersunk screw intended to be used under the lock nut.

I also reduced the diameter of the lock nut by 0.4mm to facilitate an easier fit since it is now screwed into the body.