There two models:
RECOMMENDED designed to be printed with 100% infill setting on FDM printers (stressed areas will be 100% solid, rest is "30% infill by design")
- 100% solid to play with infill or for non FDM printers
Pins can be attached to cover body using dedicated holes.
Enjoy clean range bag and no extra stuff in your upper :)
Before set up whole print try to cut in slicer and print fragment with pin holes to be sure about proper tolerances.