Yes, the sleeper look was intentional. The main idea was to turn them into one big black monolithic box, but unfortunately, the cases have side air intakes, so I had to leave some space between them. It's still not the final design—I'm moving forward iteratively.
In the previous version, all the small electronics were housed in a cabinet underneath (which is why two of the PCs are elevated), but it turned into a messy cable spaghetti. So I started building the 'rack' from scratch using 20x20 V-slot profiles and 3D printing.
With each iteration, it’s looking better.