Early in my campaign, my players hit upon the concept of EMP weapons vs my Telluric vampires, and set about googling how to make one. They found a receipe that uses flash guns and Pringles tubes, applied a decent spend on their improvised weapons lab, and I rewarded their ingenuity with during their first proper encounter with Qunicy Morris, my big-bad, fudging they EMP result, to slow him down/weaken him enough to allow them to get a couple of good hits on the Vamp before he made a dramatic escape. They've not encountered many actual Vamps since, but tonight looks to be the capstone event, and I know they'll be wanting to pull out the EMPs again. I even bought Double Tap but while that gives a nice summary of real-world EMP devices, it offers no mechanical solutions for using them in-game.
Has anyone else come up with anything?