Anyone can get tyvek free at the US post office. They use it for Priority mail envelopes. Turn it inside out.
You can use plain white tyvek as the replacement for biots on prince nymphs or color it for nymph wing cases.
http://www.rr-tu.org/Monthly_Fly.html
http://hopperjuan.blogspot.com/2010/...-nymph-20.html
You can also make stuff sacks with these bags.
http://www.youtube.com/watch?v=IyYuET-UOEk
Regards,
Silver
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy