Nice work David! I can see where the playing with the 'Bahtinov value' can be tricky in trying to get the center 90 degree line centered. I played with some variations tonight to see if the center 90 deg. cutout needed to be centered and it looks like it is a key component to the success of the "centered" diffraction spike focus pattern.
That is such a seriously cool little generator you made! Can you have a variable to adjust the right side's line angle? Also, can you group the sections together so the 90 degree slits can be unblocked (as the right sides are) so they can be centered more easily?