Some of you already have a nowadays spring reverb unit like an A-199 by Doepfer, Knas Ekdahs Moisturizer or the Vermona Retroverb.  If you really just want it for extraordinary horrorsounds, have a look for the unavailable Springatron 3000 by Nicks world of synthesizers who also made the famous Chaos Engine. If you agree that spring is more than just some fun you better watch out for the reTUBEverb as Vermonas high class model in the latest version, on sale at the time.