I was very interested in your paper on medieval chip carving, and
have had similar thoughts myself.
I have done some casting for a local medallist and he showed me the
technique for developing the plaster carving of the medal side. This
is done in much the same way, working from positive to negative, so
that a protruberance such as a nose can be increased by carving away
in the negative. All errors can be corrected to make the relief
either deeper or prouder in maybe eight or ten reverses.
This technique is described in Lanteri, Modelling and Sculpting the
Human Figure, in a section at the end. I also have a book on
Anglo-Saxon Square headed Brooches which show a great similarity of
size and general design but with different superficial pattern , I
have wondered if coarse templates were passed around and the fine
detail altered at the modellers discretion
A few years ago I did a small piece for 'Time Team' reproducing one
of the Pictish plaques that is in the museum of Scotland and was
privileged to have them taken out of the case and put under the
microscope, along with a couple of hand brooches.
You could see what shaped gravers had been used to engrave the
patterns, and in the hand brooches, small pieces of baked clay in
crevces that were too difficult at the time to clean out.
They did not seem to do this research on exhibits much, and I said
it would explain perhaps how items were made, or exclude how they
could not have been made, but they did not seem to have an avenue to
follow up on their finds.
The Curator I dealt with might remember me, I do not know if she is
still there, but having a close look at the original pieces under
magnification could tell you a lot.
I am a great believer in trying to reproduce ancient work with just
the tools and equipment available at the time, you can never prove
how something was made, but you can often eliminate ways it could not
have been done. For example I was amazed how easy it is to melt a
couple of ounces of silver with a pair of bellows and a charcoal
sorry to go on, I do not know many people interested in this sort of
stuff, I am assuming you are up in Scotland from the Pictish link.