Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4737636.
Magazine for the EK Archery Cobra 80. Holds 7 bolts, I've used both the plastic and aluminium bolts without issue.
You'll need some M2.5, M3 and M4 nuts and bolts, a length (6"/150mm) of 6mm aluminium rod and a suitable 8mmx20mm ish spring. Reuse the screw which held the original picatinny rail in place to secure the rear of the magazine. A second picatinny rail can be printed for a foregrip, you'll need to source some imperial machine screws that fit the body of the bow to attach it though.
A drill guide for the rod is included - drill the holes in the rod with a 2.5mm drill. You might want to file a hook into the end of the rod to prevent cocking when empty.
The safety needs to be removed (drift out the pin that holds it in place) and the trigger cover put into the slot to fill the hole and stop the bolts from moving back too far and jamming, it also takes a lot of the slop out of the trigger mechanism. I've added a photo of how it fits (printed in silver).
You need a reasonable sized bed to fit the magazine on as it prints in one piece.
Additional fasteners required: Front mounting: 1 x M4x40 button head screw 1 x M4 nut
Rear picatinny rail: 2 x M4x12 countersink screws
Lever assembly: 2 x M2.5x12 button head screws 2 x M2.5 nuts 3 x M3x12 button head screws 3 x M3 nyloc nuts 1 x M3x20 button head screw 1 x M3 nut
Update: Added an extended picatinny rail so both a foregrip and laser can be used.
Designed in FreeCAD.