They can be pretty complicated to make, alot of people scratch build them using wood or styrene etc but I cheated and bought a fiberglass shell for the main body of the pack so i just had to source the grebblies then assemble and paint it . youll spend more time trying to source parts than building on these things, its taken me a year so far.
Theres a ton of info on them at GBfans.com if anyone is interested in building one.
Thats a shame, we need more GB's over here .
Ive always loved pulse rifles, its one of many props on my must have list