Where did you get the intake tubes for the overflows?
Dividers are glass and used krylon infusion to paint them. Only painted one side.
Aquacave
Looks good so far. May I suggest adding union connectors? If you ever want to pull an individual tank offline, it'll be hard to do so without them. I'm building a rack as well, but plan to have each tank attached with a union connector so I can remove the tank in case I want to do a deep cleaning or want to make adjustments.
any reason you chose to install the bulkheads the way you did, i would be worried that they may leak as water can travel through the threads right out the back. which is why they are designed to be used the opposite way.. i would hate to see you get it all set up and have a constant drip at the back of some of the tanks.