That would be moi. I made seven of them in 2009/2010.
Sony told me that it had to be "mostly metal", so I used 6061 aluminum, brass and steel. The more-complex parts were done in resin, as we had a target-cost to hit and 100% CNCed metal would have put it waaay over budget (and weight).
Each rifle has a working laser sight, approx 40 LEDs, removable magazine, and power-up sound effect when the mag is smacked in.
The main structure is 6061 aluminum for weight savings. But it is still monstrously heavy.
There are about 325 separate parts. About 30 are screws/connectors. The rest all had to be made from scratch. Oy.
I still have the rubber molds for the (about) 20 resin parts. If anybody wants some resin parts, we could probably do a delio. It would save ya a ton of time and help you scale it properly...
It is BIG.