400mm Quadcopter / Multirotor Frame + Extras

400mm Quadcopter Design, made to be cut from a rigid material (hard plastic or aluminum). This is my first design, feedback is more than welcome!

Extra cuts for landing skids, and mounting plates.

Screw holes are all 3mm.

Cad drawing ratio is 1:1 (in millimeters)

My apologies for having no motor holes, I'm not sure what the exact dimensions are for the hole spacing.