DIY: Build your own vacuum tube Tesla coil
Safe is relative of course, but this isn’t quite as intimidating as some other Tesla coils out there. The steps are fairly clear, the author included a schematic, and I might just have to make one of these myself. Rather then rehash the steps here, I’m just going to direct you to go to Make and see the complete 10 step process (including parts list).
[Via Hackaday]