The Turn Of The Century Electrotherapy
How To Make 1890s Hard Rubber/Ebonite/Vulcanite Washers...
Looks like a Victorian washer!
It evolved from one of these
Which was derived from one of these...
Which was cut and chiseled from one of these!
1950s? Bowling Ball: $8.52 at a local thrift store/bazaar
2" Hole Saw: $14 at the hardware store
Making a vintage 1890s high voltage insulating washer out of a material no longer available for decades: PRICELESS!!