This 90mm quadcopter started out as you see it in the first picture, with the center stack held together by nylon standoffs and a 3d printed camera mount/"guard". After wrecking more than half a dozen 3d printed camera mounts, 2 cameras, and a motor in only the first few days I decided there needed to be changes. The new center stack is made of 4 20mm m3 screws with nylon standoffs threaded over the screws as spacers to separate the components. The 3d printed camera mount is fastened to the top of the stack with aluminum standoffs. The 3d printed top plate is attached with 4 more 20mm m3 screws which screw into the tops of the aluminum stand offs.