Nancy's dad Jack seemed to clearly remember his father tinkering with the machines until he could make patches.
Most don't agree that they were the patches which look like Master marbles. It seems quite possible that at Mr. Frier's advanced age and in the state of health he was in, he may have misremembered which patches were made.
However, I think the element of truth in that story is that patches were made. The question is which patches were made.
So, I'm ruling out the 1"-ers which look like Masters and the obvious Marble Kings which were made after Alox quit manufacturing marbles. But that still leaves some possibilities which it might be fun to zoom in on.