About this 3D model
It's a Print-In-Place model, without the need for any support material. It also takes advantage of the material properties, meaning that there are no external parts or hardware, it's just the material that allows it to flex and store energy. I was pleasantly surprised to find that the ABS/PC I printed it in doesn't break or retain a memory from being fired over 100 times. Original design: https://www.thingiverse.com/thing:1763518