I had to look it up because I had no idea what it was. It looks cool but personally I'd have no use for it. I guess it depends on your match???
Sounds like a really cool idea! Just make sure your match knows what they are receiving might constitute as a weapon, and check to be sure you'll be able to legally mail it out (depending on the size of it, etc, the shape?) From what I've seen from previous gift exchanges, pop guns and potato guns have been sent through the mail, but not sure if a coil gun would be considered differently? Contact the redditgifts people (kickme444, 5days), if you are really unsure. Best of luck!