I received several responses from MMD readers to my inquiry about
cloth piano roll leader material.  Everyone tells me it is book cloth.
I found a dealer ("Bookmakers") that carries a nice selection of
book cloth.  I ordered their "Kennett Bookcloth" which is "a starch-
filled cotton".  They have numerous other types, but most have a paper
backing.  They also sell some nice linen hinge materials that would
seem perfect for pneumatic hinges.

  http://www.bookmakerscatalog.com/catalog/bookcloth/bookcloth.htm

Philip Jamison
West Chester, PA