It was homemade by a company that manufactures rail road track maintenance equipment, at the time they used quite a few circuit boards and other rather obscure electronic do dads and gizmos
and have a read about EMC Fast Transient Burst testing.
In the dim and distant past, when I had to do some EMC testing as part of my day job, Fast Transients was a test which caused quite a few problems for some of out older equipment.
I had not seen the expression "showering arc" before today but it seems to be used to describe the arc which is produced when switch contacts are made/broken.
So, now you have some idea what it is used for, but what you can do with it? Who knows?
Rip out the insides and build something useful into the case maybe?
Might be Ok for testing Afdd's.
Arc flash detection devices, which are being made mandatory for certain electrical installations here in the Uk.
Does it have any interesting gizmo's inside.