Hi All first time posting, Long time lurker of these forums 
wondering if i could get some help as I’ve been scratch building my own proton pack and currently designing my Neutrona Wand but finding conflicting CAD models on thingiverse, already did a search of these forums but have so far come up short sorry If I’ve missed it (probably have) but not found anything solid in regards to measurements for the Neutrona Wand.
A couple of years back, members of the SoCal Ghostbusters got a rare chance to take a closer look at the “Superhero” Proton Pack, which was on display in Sony’s corporate headquarters in Burbank. During that closer look, they took measurements where they could, including of the Proton Gun: Sony Lobby Reference
Hope this helps fill in some of the info you need. 
Amazing! thank you so so much for your reply that’s definitely a super useful resource