Destructive EMP Devices

calicocat:
The person I was with when I did that spark measured 720v before we discharged it. Me being so new to all of

Likely a measurement error.

calicocat:
There's also a point that states you can manufacture explosives without any license in a certain low quantity without storing them if the point is research or experimentation,

Sounds like you are in the UK.

The 100 gram rule.

Black powder is a special case , if you make it you have aquired it and an aquire licence is required.
The law was recently changed so that a BP licence can be had as pyrotechnic use is now a valid reason to apply for one.
Other restrictions apply.
Best place to look is the UKPS who were instrumental in having the law changed.