I like to hunt. I also like to have a few extra shells on the straps of my suspension harness. After not finding a shell holder that would fit my OPW suspension to my satisfaction, I decided to make it on TinkerCAD. This is a clipped, double shell hold that is designed to snuggly fit standard 25mm or 1" strapping found on may suspension and pack systems. If your pack uses 20mm (3/4"), modify the clip-base. https://tinkercad.com/things/e1uKCSv9Ohi-clipped-double-shotgun-shell-holder#
UPDATE: I added a split-clip version after a buddy saw my original. He wanted to be able to clip across the webbing sew-downs, so I split the clip, then had to thicken to prevent easy breakage. Seems to work. You can find it publicly on my Tinkercad page - tjstroker
I print on a Makerbot Replicator 2. with STANDARD settings. Also found the FAST mode works fine as well. I tapered the clip edges to make it easier to slide in and our of sewn straps, but it still fits snug. If you wish to use with packs/harnesses with smaller strapping, like my Gregory 55L pack (3/4" straps) just go to Tinkerbot and raise the clip-base height a few clicks. I wanted it to fit precise to minimize tilting on the suspension.