I know a few of us make thinner head shims for the diesel conversions using heavy alum foil
(broiler foil) or Alum beer or soda cans at least on the norvels and coxes I found a neat circle cutter yesterday in an local HS made by OLFA model cmp-1 complete
with extra blades $10 it goes from 0,4in dia thru 5" I guess its for making circles
for covering materials such a monokote etc I think the alum cans are 0.004 I
loaned out my mike so not sure on that part