geared dc motor mount for physics experiment

recently our physics teacher asked us to experiment with something like a dc motor ,pulling a little weight up and caculate it's efficiency,however we don't have the equipment in a short wile. luckily I just have one of these dc motor which turns slowly since it has that nice gear inside.so I designed some parts and printed them in PLA(of course I more recommend something like PETG so that it's more temp resistant)it holds a dc motor to a vertical rod firmly
the diameter of the rod needn't to be 10mm that I use.a little bigger or smaller of a diameter is fine
you can download the step file to tweak the design
I used brass threaded insert but you can change the hole to a slightly smaller size than the bolt and just thread in
get the print orientation right to get the strongest part and add support if needed.
in my case one part has a curve like:shang
part ........./
part↗___BED
↑
so add some support here