3D Robotics Multirotor Reinforced motor fixing

An improved motor fixing for 3D robotics multirotor frames. I've found many times when I've had an uncontrolled landing with my drone (sometimes upsidown!) That the aluminium arms get bent where the motors are bolted onto them. This weakens the frame and in extream cases can cause the motors to become loose and detach completely.

These two parts along with 2 M3x25mm Alen head bolts completely solve the problem. The main part slides inside the box section making the aluminium significantly str