These are the gaskets for the Edmund grey 1" shaft mount setting circles. They are 1/4" thick rubber. The originals are a few thousandths over, these I made are a few thousandths under 1/4". The thinner size will let me ship in a regular envelope.
I use a circle cutter. There is a lot to be cautious of with one of these, in particular you are spinning a long bar. That bar will hit will hit everything from your hand to your clamps to everything. Do a complete dry run test for clearance. Each blade is at a different radius, one cuts the inside while the other cuts the outside. You need to have the cutting edge face the right direction. INside cutter faces out, Outside cutter faces in. The rubber needs to be clamped securely under a top piece. I drilled a 3" hole in my top board to clear the cutter parts. You should set the blade depths so the inside cutter finishes first, then the outside cutter frees the ring. The other way around won't work.
Inside diameter is 1.9", outside diameter can vary but close to 2-1/4". I make the outside a little bigger than original but not large enough to cover circle print.