@ Andy and Richard; yes, to discourage misuse. Always a bit paranoid, though I like to show stuff and encourage other TG users, I can't often post large finished (commercial) images, at least not without any form of 'disfiguration'.
@ Bobby; yes, I think I've tried almost every node and combination, but the stroke is too hard for a moat. I do have a setup with 2 SSS and some subtraction, but the corners are always a bit too sharp. So in this case I have simply painted a simple grey mask in PS, set it at 0/0/0, and located/rotated that on 2 locations through 2 transform shaders.
This render will be blown up to 80cm wide and framed as a farewell gift for an archeaologist, so, though I started it as a private thing, I didn't make it for nothing.