How to make a plastic pocket holster…. out of a milk jug.
From Claude Werner (h/t to Greg Ellfritz)
I’m not saying this is the right and best way to do things, but it’s something to keep in mind, because certainly this could be useful.
(and please, don’t show up to class with one of these).
Stuff From Hsoi 
I did something similar using a plastic mouthwash bottle and couple of boards in a T formation to make a bed holster similar to this http://s280.photobucket.com/user/dbeardslee/media/XS11/temporary/BedHolster.jpg.html
Nothing like DIY 🙂