I recently did a one-off set of keyfobs for a fellow GBFan’s RGB project. (Well, I did 2 sets actually but kept one for myself because y’never know…)
Possibly would be suitable for a steampunk Ghostbuster? 
Using the same high quality construction and materials as I use for my regular keyfobs but with solid brass fittings and brown leather! (Typically the photo photo below doesn’t do it much justice, I will try to take some snaps of them later with my “good” camera with better lighting.
Leather is Heavy Duty ¾" Wide Brown Cowhide
Brass Plated Press Studs
Solid Brass Heavy Duty Clip
Solid Brass 1" O-Ring
Solid Brass ¾" D-Rings
They worked out more expensive as the regular fobs because I bought such small quantities of the brass hardware and leather (I usually buy in bulk; enough for 25 sets, but only bought enough for 2 sets with these) but if there’s enough interest to do more, I should be able to get the price down to something close to my regular fobs! (To Be Confirmed)
I also did a leg-hose fob (not pictured) using the same leather!
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Whaddya reckon…?*