I started this build in February and finished it just in time for Comic-Con! It was a big hit at SDCC, people were stopping me everywhere to ask me where I got it, and the look on their faces when I told them I made it was priceless. And as it turns out, my gun is in many ways more accurate than the NECA replica because the majority of the outside parts were 3D printed from models made directly from the game. It has lights and sounds which are triggered by buttons under the back shell, and all the electronics are stored in the back of the gun.
A video of the gun in action