Honestly this is a great piece of workmanship, having integrated the necessary equipment into something completely innocuous that does generally get ignored or overlooked. And the fact that the printer still works with this extra hardware, is a testament to how little you can assume any piece of equipment is safe/unmodified. Interfacing the cell interception with the printer is just gravy, a real undercover device wouldn't do that, but it's neat.

The disguised cell towers aren't "the meat", they're, as described in the post, just "conceptual background". Possibly irrelevant background, as they really aren't intended to be secret surveillance devices in those cases.