My guess is the wad finger you show was injection molded, so tooling must exist somewhere.
Teflon bar stock is available and it might be pretty simple to turn the shape, then slit it.
If you remember back 50 years ago, the wad finger in the 600 Jr. press was made of brass, not the red plastic everyone replaced it with. I know how that part was made, but knowing that, and having the funds to make the punch press tooling are miles apart.
I think turning a piece of teflon is the shortest route. And yes, I'm aware of the fact the burning, or melting teflon generates toxic fumes.
McMaster-Carr has Delrin rods, which would be a good material.
https://www.mcmaster.com/teflon/multipurpose-plastic/
Threaded Mode