Thanks for sharing additional details! An instuctable wouldn’t be a bad idea :)
So you have the same CLK going out in parallel to your 9 rows? Does that mean you’re using WS2801 or similar LEDs that accepts a clock signal? I had started building a 6x6 grid prototype, but I was using WS2812 LEDs. They work great at the size I’m prototyping, but I suppose I’ll run into signal switching issues when I get to sizable lengths. I can’t really split them out into parallel blocks because there’s no separate clock signal, I might try a larger length test and think about switching to WS2801.
What material are you using to diffuse your LEDs? I’m thinking about frosted plexiglass(Acrylic) blocks