Materials: Your choice! - You could use flex-filament to avoid a break. I used pla. Difference between with/~out support structure, vertical print, draft pint: hardly any/absolutely acceptable - i lost two/three threads of pla without support and lost one layer in the unevenness with support. Nevermind! - It will get scratches, if you do tricks with your ninebot. Methods: You could use washers (i did not/was not neccesary). You´ll need screws from your bike shop (my diy market sent me there) and a hex/allen key. Size of the screws - as far as i remember: M4 16mm (europe) - PLEASE VERIFY! - and whats the size in the america? - Nr.8?