Z axis motor mount for 48mm motor (for Skeleton3D)

I didn't have 40mm motors at hand for building my [Skeleton3D](http://www.thingiverse.com/thing:560353) (awesome little thing!) so I re-used some 48mm motors I already had.
While it's ok to do that for the X and Y axis, for the Z axis the longer motor doesn't fit.
So I opened the original mount in blender and enlarged the "neck" by 8 mm to accommodate the longer motor.