Alright, managed to find my template hidden amongst my big ol' pile o' templates, lol.
I was correct in recalling I'd used the same thickness as I did for my last Medkit build.
The measurement for that was 3 1/4", which as I mentioned before looked right by my eye.
Hadn't thought of hot-stamping for the circuitry pattern. Honestly, I'd never even heard of it before, lol.
I think the cost involved would be similar to silk-screening, so wouldn't be preferable.
A metallic, chrome or metallic finish wouldn't be screen-accurate, so I don't know how many would want that.
EDIT: Upon closer inspection (thanks in large part to that WiP pic @norbauer posted four days ago), it would appear that the thickness of this device is not the same as the Medkit. The dimensions of some of the plant-on elements don't match with 3 1/4". Looks like the thickness is slightly less.