I don't have many pics left of the build. It was a few years back. They don't even make the boards anymore. The boards are
HLG QB132's in 3500k. The PS's are Meanwell LRS350-36's. I built thee frame out of 36" angle aluminum strips that you can get from Lowes and home depot (standard length is 36"). The boards are wired in parallel. The PS's only have 3 channels, so one channel per PS has 2 boards on it (still in parallel - the PS still provides full power to all boards this way). I've never checked the PAR. I lower the light if they're stretching, and raise it if I see stress. Usually run around 36" above the plants.
These boards don't need heat sinks. I have an infrared pyrometer that says the boards are around 135°F when on (painted a dark spot on the back to get accurate readings). Ambient temps where I grow range from 50-110°F and u don't run an AC. The boards raise tent temp ~5°F at 300w, and 7-9°F at 600w. I have a 440ft^3 per minute blower that draws suction from the top of the tent to try and evacuate as much heat as I can. It's pulling through a 6" duct though, so I'm probably getting less than 200ft^3.
I'm currently growing autos so I don't care about light leaks. I run suction in an "S" through the lower tent ports when growing gems to prevent light leaks.