Hareline Medallion Sheets
A few years ago one of our guide friends turned us onto 3M Transpore Tape (thanks Dan). We made some wing material out of it that is hard to beat. Take 2 pieces of Transpore Tape and sandwich some Hareline Medallion Sheeting in the middle. What you get is a durable, realistic, waterproof wing material that works great on hoppers, stones, and attractors. The finished product is pliable for tying but rigid enough to keep its form after being chewed on a few times.
This is the same stuff Umpqua uses on their Rogue series stones except they use a die bath instead of the Medallion Sheets. I have heard that Medallion Sheets are hard to come by now but you can probably use Swiss Straw for a substitute. The tape takes color well so you can use markers to color it to your liking.
While working at MFC we let them in on the Transpore Tape and they now produce a similar product called Flex Wing. Flex wing uses the tape on one side and a treated paper on the under. We like ours better of course.