How about using a compass with a # 11 blade where the pencil goes, and cut them from alum pie plates.?
  The plates are about .003 thick, or from some .005 brass shim stock?     

Allan, I have made a few of these as required.  This one is just made from bits of mild steel out of my scrap box.  You do need a lathe of course.  The fits need to be very close as you are going to shear the metal of the shim, and if the parts are loose it will not cut cleanly, but to make just a few shims I have never bothered with hardening the metal. To use take a small piece of your shim material and cut a hole near the centre - the hole can be a bit ragged, but try not to distort the sheet while you are cutting it.  Place the central spigot through that hole and into the guide hole in the mating part and press together to punch out the centre hole.  (It can be done in a press or bench vice).  Now slide the third part over the central piece (which aligns it) and press together to shear off the outside scrap.  Now pull the 3 pieces apart and you have one shim and 2 bits of scrap to prise off or out of the cutter.

David, The ones that I have made have successfully cut soft aluminium sheet of about ten thou (mils) thickness.  The fits are about like a worn out piston and cylinder in a model engine - that is a free moving but rattle free fit.  For cutting the thicker material that you would need for glow plug washers you may need to experiment with different designs of punch.
Charlie

I use a 1/4" paper punch to cut the inside hole, and then cut the outside with scissors. If you cut the inside first with the punch, then you can finish out the hole with a Dremel with a sanding drum before you cut the outside. That way you have enough material to hang on to.

Guess I will get myself in trouble again, but, contact Jim Lee at Lee Machine Shop.  He is a vendor on here.  Head shims or gaskets made with his tool.