This is a replica of the shotgun shells used in the TV show The Expanse for Amos Burton's Auto Shotgun. These are sized up slightly to better fit the shell holder on the stock of the shotgun, which is designed for the 30 round magazine shells used in airsoft shotguns. They used Hakkotsu green gas shells for the show, and the real ones are just a little bit small for those holders.

If you're printing this on a filament printer I would recommend printing the swirl insert at 0.05 layer height so the detail is preserved.

I'll be uploading the tray to hold shells very soon. Stay tuned.