I know that I’m not the first person to do something like this, but I think my take on it is unique.
It started life as a Nerf Jolt. I cut the barrel off, and made a new one from 1/2″ CPVC. I used an old Recon catch spring and a piece of ball point pen to rework the trigger.
Here’s a link to a write up that helped me solve those problems. http://nerfhaven.com/forums/index.php?showtopic=21954 It’s by a Nerf Haven user named iamthatcat.
The armor plate is heat shaped PVC, and the straps are small dog collars. The feature that I am most proud of is the ring trigger. It fires with a flick of the wrist.