Very thin sheet cork is available from

  Creative Impressions
  227 Neosho
  Burlington, KS 66839
  tel.: 1-620-364-5178
  http://www.creativeimpressions.com/ 

The cork comes in letter size [8.5" x 11"] size sheets, five sheets
for $5.  The thickness is about the same as gaskets used in Ampico
stacks, 1/16th inch.  It is sold as cork-paper for children's crafts.
Used as gaskets for striker pneumatics it forms a stronger bond than
blotter paper, which is much easier to remove when necessary.  The
quality is excellent.

Bill Chapman
in sunny La Quinta, Calif.