when it comes to pick holders, they often involve little 3M stickies and limits your options in positions and instruments to use it on. This little thing takes less than 2 hours to print and fits onto most acoustic guitars. Classical and electrics don't work because of different neck angles and string directions. This holds 3 picks of plenty of thicknesses. 

Sorry about my picture standards. I took down my lightbox to make room for my new printer.

This was designed and printed for the Cort 20th Anniversary Earth model. I also tested this on a Yamaha acoustic and an Epiphone SG Pro. The Pro didn't work because of neck angle.