On Wed, 25 Apr 2012 11:34:02 -0400, "Flying Pig"
wrote:

What kinds of places would use Mylar patternmaking material where I might
obtain some scrap (I only need ~4" square)?

===

Sailmakers will definitely have some, possibly canvas shops. You can
usually buy individual sheets at art supply stores. It's also
possible that you could use a small piece of Strataglass or something
similar. Canvas shops will definitely have that.