Dear Alison, I did this quite a while ago and had quite good results.
I kept one of my prototypes and have just had a look at it and it’s
still looking good twenty years later. All I used was the thin but
stiff plastic sheeting from a shirt box (I know it sounds trite and
not very professional jeweller), made up some strips of U-shaped
silver and/or gold using 0.3mm metal, 4mm wide so that when bent into
the U strip it ended up about 2mm wide.
I cut my squares of shirt-box clear plastic so that they projected
about 3mm all around the stamp then using only the thinnest smear of
epoxy glue so that it wouldn’t squish onto the stamp, sealed the stamp
between the plastic sheeting. I then fitted metal U strips neatly
along each side and chamfered the corners like mini picture frames and
simply pushed them into place, making sure that everything aligned and
was square to the shape of the stamp. (some of the stamps were
The unit could then be set into whatever you wanted. I used gold wire
as an attractive feature and contrast to the silver frames.
Rex from Oz