I've just tried building my own one. I bought one of those induction heaters off ebay. I took apart the coil that came with it and wrapped 6 turns tightly around an old protank mini 3 glass. I plugged in a LiPo battery directly (just to test everything). My quick little test setup looks like this:
https://imgur.com/a/RYJvc
When i plugged in the battery, the blue LED was on solid, so I thought everything was okay. But as soon as I introduced the vapcap into the glass there was sparks on the ZVS board. So I immediately pulled it out and disconnected the LiPo. I'm too scared to try again. What happened, what have I done wrong? Is my coil too short? Any help would be appreciated here.
edit: I just plugged the LiPo back in, the LED still powers on solid blue. Too scared to try inserting the vapcap in the coil until someone can tell me everything is kosher or I've done something horribly wrong.