Customizable Flashlight Diffuser Cap

Parametric diffuser cap for flashlights.
--- Update 2014-06-18 ---
Add the ability to put a notch in the side wall to make room for a lanyard to allow storing the diffuser on the back of a flashlight with a lanyard.
--- Update 2014-11-06 ---
I wanted to use a Cellphone charm strap to hang this off of my Fenix LD01 (because, of course, I lost the previous one) so I added the ability to create a hole in the side opposite the notch, then printed a new one out in glow-in-the-dark filament.
--- Update 2015-05-27 ---
Added anti-roll feature, the ability to specify the length (to make light wands) and a few pre-rendered versions for flashlights I have on hand.