Lots of videos on making the stuff..if not..Home Depot for the 50 cent sprinkler coupler (it has little "shelves" built in (stops) that hold the nickles in place perfectly.
I used a nut driver to push out the puck..anything will do..BTW..use a piece of half inch PVC and a piece of bamboo support pole to easily turn the bags inside out. Purepressure gets an absurd amount for their pre built "tool" lol
I never tried a 1inch or 3/4 inch piece of pvc though..just might fit a quarter inside one of those couplers. More PSI in a smaller area is what we want.