I cut the boards to the height of the tubs, I used the same sterilite tubs that the boaphile sideways sweater box rack uses specifically because the 15 and 32qt are the same height. All if the wiring comes out through openings in the removable back panel. I will post pics when I'm installing the flexwatt so you can see the wiring with the back open later this week. I may also put a strip of flexwatt on the open top of the cabinet for use with smaller hatchling tubs and a temporary placement of tubs while cleaning etc. .