Crosshare holds monthly contests for making midi-sized puzzles, and the current one ends on 9/24. This month's theme is "crosswords that contain at least two sets of 2x2 blocks all filled with the same letter."
Thanks! I think the 'official' spelling is indeed with an 's', but I have seen the 'z' version in windows and on chalkboards of a couple dispensaries (I live in a legal state although I do not partake myself) and online. I agree that "informal" may not quite do justice to how unofficial the 'z' spelling is, but that corner was a nightmare!