PS. Reliability on the first one I made about a year ago (now on my GF's son's boat) and the newest one has been excellent though one reader here said they had two DMM's go bad. I have several of the DMM's being used, one in a solar panel, two in boats and one at my battery charging station and have not had one go bad. As a matter of fact, I've had a few running full time 24/7 for over a year without a failure.
Even though the sellers "claim" that the components are marine grade, I bought a couple of spare switches, a voltmeter and USB outlet. The panel components are all pretty standardized as far as mounting holes go and if something goes bad they're easily sourced and replaced. I took the precaution of having my GF make a clear plastic cover for the panel. If you mount it on / in a boat bench or existing console I think it would be a good idea to fabricate a way to protect it from water intrusion.
Also IMO think big as far as switches go. Mine has six switches on the commercial panel but I added more switches and three extra outlets. There's a 10 switch panel model out now, If it were available when I designed my console I would have bought that one... it would have simplified my design and fabrication.
SAE QD polarized connectors to rear panel
1 Bilge pump
2 Front flood light
3 Instruments (Depth finder)
4 Accessory
5 Cooling Fan (Yup it gets hot down here)
6 Separate 180 degree stern light
7/8 Dual rocker for Bow / 360 degree pole anchor light
9 Horn
Panel mounted internal switching (no SAE connections to rear of the panel)
10 Master fused power switch
11/12 Dual rocker for Green and white cabin lights