Slim pen holster

Tweaked this model to hold a Surface Slim Pen in then center, and reduced the diameter of the lower hole for a more normal sized pen. Makes it a slightly slimmer profile. There are still a few voids around the surface pen hole that could be filled in, but my software kept crashing when I tried to do those last pieces. Doesn't affect the stability of the part.

Original here: https://www.thingiverse.com/thing:2757690