Interesting topic -- I found a good video that describes the process and the variability of results between a microwave transformer and a neon transformer. He also stresses the safety issues.
https://www.bing.com/videos/search?q...5D7D&FORM=VIRE
There are a lot of really bad videos out there -- One guy was handling 2 hot probes with bare hands! Good recipe for electrocution.
Cliff