This is key No 147 It is a "loose" copy of a Swedish Military key, It proved to be quite difficult to make as it has a complex dual isolated contact arrangement, where one set of contacts can be used to isolate the main key arm from the connections, presumably for when the key is keying high voltages, below are some pictures of the finished key with the original that inspired it, a lovely key with a really nice smooth long lever action to match, I was going to Nickel plate it, but interest has waned in that direction :()