Pipe blaster - trigger and hammer double action gun

Fallout 4 Pipe Blaster remix, with a trigger and hammer mechanism.

How to Build:
4x 3D parts (1xhammer, 1xtrigger, 1xSide_cover, 1xSide_cover_2)
3x M4 bolts (16-20mm) + M4 Nuts
small rubber bands (2 or more)
https://www.amazon.com/Orthodontic-Elastic-Rubberbands-Dreadlocks-Horse/dp/B00OT8QVKC/ref=sr_1_6_a_it?ie=UTF8&qid=1469969242&sr=8-6&keywords=rubber+bands+braces