I was under the impression that @Mob of Blondes felt it important to have squares near the center of the Silhouettes for gameplay purposes. If it's not so important I could do a stepped fade of some sort (since I'm trying to avoid soft gradients personally on my designs). If I was just making them for me, I'd probably just go with this design for clean aesthetics: They don't have the guides, but I feel like once you're trying to eyeball a 3mm square from 36" you should be playing with surveying tools and not little cardboard squares that you have to manually position anyway. Either that or come up with some 3mm magnets and stick them on both sides and then drag it around to find your spot. Call me crazy but I always assumed 3mm just sort-of a 'minimum perceivable area you kept roughly in your mind but not something you actually physically tried to measure.