I'm not sure why you
don't want the cover to touch the spindle. Here are the ones I 3D printed for my M2Pro:
Mavic 2 Motor Cover
The cover goes over the
outside of the motor mount, instead of fastening to the inside, in the same way the props are fastened. By going on the outside
and covering the spindle, they provide complete lateral support for the spindle. Many of the other covers I looked at leave the spindle exposed and I was very concerned that, during transport, one or more of the spindles could be bumped or pressured laterally, resulting in a bent pin.
In this design, all the lateral pressure is transferred to the outside of the motor mount, something that is much sturdier than the spindles.
These covers also provide complete protection from dust and debris getting down into the motors or coils.
I think there are commercial versions of roughly this same design.