I believe the plates were made by painting the entire plate and then
buffing off the paint from the raised brass lettering, borders, etc.
A very hard buff would be used so that it skimmed only the raised portion
and not the recessed paint.  These are commonly made today by restorers
of antique automobiles who replace nameplates, patent data plates and the
like.

My understanding is that most escutcheon pins are basically a brad with
no point.  I would think many applications could be served by using a
brad and either cutting off the point or leaving it on.  This would
certainly serve for attaching label plates and the like.

There were some with funny heads that would have to be produced by
turning them on a lathe.  Find some retired toolmaker or model maker in
your neighborhood and put him to work making small quantities of these by
hand (on a lathe).  A lot of these fellows have rather nice metal working
shops in their garage or basement and are just looking for some small
projects to bring in some "pin" money.

Bob Conant
Endicott, NY