The parts were wood discs that the customer sent in a box from time to time. Not hockey pucks.
Cams are super simple and work fantastically for this application.
You can use vacuum for this as well. A Gast or Welch pump is what I'd recommend, although a Harbor Freight one would work too. Gasketing is a must for these pumps. You *may* be able to sneak by with a Lighthouse vac et al or Fein Turbo III. You want 'open vacuum air' to touch the backside of the puck. No ultralight MDF bleeder board - or it won't work. See BradyVac II on SB main site.
-B