I used SIG Coverall or Koverall on this.
Attached with nitrate dope.
I cut it on a diagonal bias.

Dacron or taffeta from fabric store.  May be the same stuff.

Here's a hint.  Take a piece a foot or so square.  Iron it smooth.  Using a light pencil and straight edge, draw out a grid using whatever size hinges you want; 1/2" by 1" or whatever. 

Next, take a striping brush and run a narrow line of dope over the pencil lines.  Let dry and cut on a cutting board using a straight edge and sharp razor. I like the double edged blades broken in half.  They seem to work well on the fabric. A number 11 blade tends to snag the threads. Or better use a fabric cutting wheel. 

You now have nice uniform hinges and the edges wont fray when you handle them.