I hope you see this and respond Pat, I read your tip about the butter frame and want to ask a question.
After reading your tip on using a frame to roll butter into a light went off in my head. That sounds like a great idea for building a consistent size and thickness of butter, if I understand what you wrote. So the first thing is to figure out what the cubic volume is in a block of butter. Next decide how thick you want the slab to be and mill some hardwood to that size thickness. I'm thinking that 1/4 to 3/8 inch would be a good thickness as it it twice the thickness of the final roll out and would be the same thickness as the dough roll out the first time. You would tap and roll the butter (encased in parchment or plastic) inside the frame and flatten it. Removing and chilling the butter after for later use.
The hard part of this will be determining What the volume is of the amount of butter in your batch recipe. There would be minor differences in weight/volume ratios between various butter makers depending on water content but these would be so small I think not worth bothering with. I usually use the English method of encasing the butter whereby I form the dough to be 1/3 longer than the size of the butter. So then, I need to make a frame about 8 inches wide on the inside and long enough to equal a pound of butter at say 3/8 inch thick or what ever that thickness turns out to be.
Is that about right Pat? If this works out, it will resolve my main issue with making croissants, which is forming the butter.