I recently came across reference to something called "chaser's pitch".
It is apparently a self-made concoction which is thixotropic.  If you
contain it somehow with the intended escutcheon plate as one surface of
the container, you can form the metal by hitting with a punch and hammer.

Under the blow, the chaser's pitch moves, but around it it remains more
or less solid.  If you put the intended exposed surface against the pitch
and carefully 'punched in' a design like you need, a fairly faithful
replica of  the original might be possible.

When finished the plate would have to be 'cleaned up' on the intended
exposed surface with files, burrs, whatever, and then polished.  Finally
the paint could be added, and then buffed off the raised portions.

This is, I believe, all based on the metalworking process called
"chasing", which I never heard much about.  I intend to discover more.
Hope this adds something to the discussion.

Best wishes,

Richard Danzey

 [ A chaser is "one who chases, or engraves," says my old dictionary.
 [ -- Robbie