Mylar sounds like a great choice to preserve the music roll itself,
but it is very abrasive and would probably wear the tracker bar down
quickly.  I think that replacing the paper every so often would be
more economical.

Then there is Tyvek, which is quite stable dimensionally and quite
tough but much less abrasive.  It is not easy to perforate, though,
and neither is Mylar.

Spencer Chase
http://nt.mcn.org/spencer/