Making rounds by fusing squares

[Jack Bowman]

My search on this topic comes up empty.I want to make round cabs/disks by fusing stacks of squares. I had it dialed in, and then they changed the diameters. I was stacking up to 7 small squares to get a round disk. I need to make 1.5", 1.75", and 2" rounds that will naturally be 6mm thick. I'm using 3mm BE in various transparent colors and heating to around 1500F. Has anybody done this and worked out a formula for the size and number of squares? I'm going to do more R&D, but I'm running out of time. They changed the sizes but didn't extend the deadline.
Thank you, Jack