A good household glass or mirror shop should be able to make one easily and fairly inexpensively. An artglass workshop will also be able to do it. I made one myself once. It took about three tries, a diamond drill bit will bore the hole for the light dimmer shaft. A special grinding wheel is needed to finish the edges after cutting the glass.
Some of the instrument rebuilders should be able to get a replacement glass for you also.
Joe Alexander
Blacklick, Ohio
