Looks really good. I may 'steel' this tower idea to use on a bar back type fridge in our basement kitchenette.
One thing I would change, just visually for me, I don't like the look of the 3 sections, especially when it translates to 3 different drip trays. Is there any particular reason you split them up?
I noticed on phillipCT's thread, same tower as yours, the exact same thing right away; he had a recessed drip tray in the fridge top, and his flanges went over the top of it a little bit. I'm thinking I will put all taps in between two towers with elbows. A single cross pipe allows for 1 drip tray to fit without interference anywhere.
How heavy is that thing? Easy to lift the keezer lid? I see your safety chain there, good idea. I imagine you need a lot of clearance behind keezer when opening the lid. This is swaying me towards a front open, bar back type fridge, as I don't think I could make that work in the space I'll have.
I glanced at grainger and quick math showed a 2' cross pipe, 2 elbows, 2 flanges, and 2 risers about $400, all in 3", does that sound about right? Would you say 4" would have made it any easier, or that 2" would have made it harder?
Is the gray flex pipe going up into tower for cooling? Do you not need to cool the other side?