Not as pretty as the lockwork, but functionally important to the works of the loads, here's an image of the tools I use to make the cup-shaped OverPowder cards and an illustration of how the donut-shaped felt wads I use work with the roundball.

Arch punch cuts milk carton discs, then they go through the die that's resting on the arch punch via the brass punch.
I transfer them into the cases via the knurled ring - that makes getting the skirts into the case mouth easier.
Then goes a disc of lubed felt followed by one shaped like a donut - followed by the roundball.
The roundball shown there is on top of a donut which is on top of a disc.
See how the donut 'squishes' out under the pressure?
That's what happens in the bore. Great gas seal and great greased wiping of the bore.
That's backed up by one of the cup OP cards which are under constant pressure with the bore as well.
Great combination, ultra cheap to produce, and the components are available almost anywhere.

Cheers
Tinker