On my Targa 27, I bought an 80W solar panel and dual charge controller from Photonic Universe to keep my boat batteries topped up:-

This handy charge controller can be set to prioritise either battery bank. I have mine set to 80% for the leisure batteries and 20% for the other engine starter battery.

Clever device; when one bank reached full charge, it switches 100% to the other anyway.

The charge controller has an output for a battery/charge monitor which I wanted to fit to my dashboard.

I didn't really want to drill another huge hole in the dashboard, particularly as it has an improvised panel covering a large one that presumably held some kind of instrument at one time.

Unfortunately, this panel was rather ugly and would look even more so if I fitted the new battery monitor to it :-

So I decided to 3D print one instead. This is my design:-

The main panel is too big for my printer but I used the Autodesk 123D CAD software to split it approximately in half. The backface cover (left) and mobile phone/pen holder (right) will provide additional strength when it is glued together.

Here is the printed panel after assembly:-

And here it is fitted to my boat :-

The mobile phone holder is really useful (for some reason they left this off when the boat was built in 1991 !) :-