This is a backpack for Dummy 13. It prints in two parts: the body and the lid. The two parts connect together using a pop hinge. The hinge pops in place by aligning the lid with the body in the closed position and pushing/wiggling the two parts together. The backpack can then be attached to Dummy 13 using the square peg, which snaps into the square hole in the dummy's back. 

Printing will require supports for the square peg, a threshold angle of 10 degrees should work nicely. Recommend using .12mm layer height or less to help with hinge fitment. Have been printing these in PLA but PETG may work better for hinge strength. 

Version 1: Original design with large lid but less capacity.

Version 2: New design with smaller lid to increase body capacity. 

Use hinge lock to tighten things up and lock backpack closed. Hinge lock slides over the assembled hinge when in the fully open position, with flat bar inside the backpack and pointy ends outside, see pictures in gallery.