Okay, wait, let me quote from the textbook with a chart:admin wrote: But I still don't quite get about the 57% ratio. If I understand right, the square material inside the circle must be thick and durable enough to withstand pressure? If so, that explains the 6% discrepancy since the square need those 6% of areas for its border.

Center of graph is true position
Plot delta coordinate values for feature locations on graph
Create concentric circles representing tolerance zones at same scale as the graph grid

Edit: Also, glade you were able to create the circle/square option.