Referring to Luis Nadeau's Encyclopedia, there are several processes that resemble what has been described here: Relief photographs set with plaster or wax, frequently hand coloured. At this time I haven't any details regarding the "how to", but I'm hoping to hear back from Luis soon (if anybody knows, it's him)
My first post, hope this thread is still alive.
Many years ago someone who ran a charity shop showed me a couple of "prints".
They were relief prints on metal. both portraits, had never seen the like before.
I took photographs of both back and front. One of the prints was damaged and there appeared to be plaster under the metal surface.
I asked many people about them but got no answer.
On the back was the word "PIRIM" and between these large letters it said "Portraits in relief in metal"
the address was given as "40 Pall Mall, London SW1" also Patent numbers 397798-418268.
The reason for me posting this now, is that I was searching through an old back up drive, and came across the image,
I decided to Google about and this thread popped up.
here's a newspaper article on the process
when they opened up their north american headquarters