[BalefireX]

Assuming you have a thick enough base, covering the entire TEC shouldnt be vital, correct? True, the Maze4 doesnt cover the corners, but it seems to do okay as a TEC block anyway. The only other way I can think of using the lumpy channel design without being massively restrictive is to do 50x50mm of parallel channels and then make a custom middle plate that spreads out the flow of water from a 1/2" diameter inlet to a 2x50mm channel perpendicular to the lumpy channels. See attached pic for concept