An obvious - Be Careful
Whilst the Diecast box is more rugged and will act as a heatsink for the charger, it IS conductive. Absolute care needs to be given to insulating all + positive wires from the box/lid and when positioning any uninsulated terminals. Probably preaching to the converted here, lol, but.........
Otherwise a very neat setup Bigwave, great job.
BTW the reason I used a plastic box is that my setup is permanently mounted in the rear of the 4by, tucked behind the fridge and away from being damaged. I don't need to move it as I have a separate BCDC in the caravan and solar controller.
And, the reason for this is that I need charging in my 4x4 at the same time as in the van when driving. As these chargers should be as close to the battery they are charging, it's problematic trying to charge 2 batteries 6-7 metres apart with a bigger charger. I also use the 4x4 BCDC without the van hookup
Bigwave's setup and mine show how we all have different requirements
and therefore different solutions
FYI - The Redarc range of chargers are built to NOT need heatsink mounts, however care should be exercised in their mounting location, they can and do get hot especially in summer.