Back when I plugged my own balls, there was a company called Dascar Plastics that made a two-part resin, called RP-40, used for pouring fast-curing molds. I used it in bowling balls for years and never had a problem with it even though it would harden in about 30 sec - 2 min and be drillable in a couple of hours. It punched 75 on ShoreD, so it was appropriate for USBC durometer specs.
The problem with it was color. You originally got one choice: white. Perfect for plugging AMF XS and Quantum Bias balls, problematic otherwise. Then, they started selling what they called "clear," (RP-40 MOD I think it was) but it wasn't clear, it had a yellow-tan tint to it. I never really tried to color it so I don't know how it would have taken to colors.
But you could get it 1 quart at a time (or 1 quart of base and 1 quart of hardener at a time, to be accurate). Good price, too.
Their website is apparently down, so I worry they're no longer in business. Several YouTube videos out there from people making stuff out of their resin. The times I dealt with them over the phone, they seemed like a very small operation. They used to ship their stuff in recycled motor oil quart containers.
Jess
