I see this piece in the parts list, but I'm not sure if we are supposed to 3D print it or purchase it. It's hard to tell how many teeth it is from the picture. Can you share some more info on this part? The one I'm talking about is on page 9 of the Robot Arm assembly manual.
I see the part, thanks for clearing that up.
Your aluminum kit should have an aluminum version of this part. When I made the manual I didn’t have an aluminum version yet and was 3D printing the hub. Either should work fine though.