Thanks a lot folks! I can't rightfully say it's a redo of the Mattel figure since only the equipment and the rubber tube are from that figure. The original figure is still sitting in the box and I have no idea what to do with it now!
Here is a photo I snapped of the back of the containment unit:
Not very glamorous. There are a few resistors soldered in there, but I am not an electronics genius by any stretch of the word.
I DID do a lot of research, but technically it wasn't for this figure. One of my other hobbies is building replica movie props. I did a ton of research about 7 years ago to do a full GB costume, from the proton pack to the PKE. Here are a few photos of the trap and PKE:
All the props are screen accurate, using the same electronics parts that were used on the originals (even purchased from the same surplus electronics store that the original parts came from). I went to this place and dug through decades of dirty boxes. Coincidentally the guy who built the original GB trap was Jamie Hyneman, the guy from Mythbusters.
I used the info from that to make my figure more accurate. I was so into the Ghostbusters props for a while that I was part of an online community where we collectively researched this stuff, tracking down the original props and makers, analyzing them, etc. I'm proud to say, that GB trap you see in the photo is the ONLY full metal replica of the Ghostbusters 1 style trap (they differed from the GB2 trap) in existence as far as I know.
I am positive that the work me and my online buddies did was heavily utilized by the Mattel people when they researched their figure. All the info is online now, and we really discovered a lot of those things, like the types of knobs and valves that were used. It's not like Star Wars props where George Lucas has an archive for his licensees to access. The GB stuff is almost entirely in private collections, or places like Planet Hollywood.