We Yorkshire folk, even those of us living in Derbyshire, hate wasting stuff such as the very expensive polypropylene yarn like the Tiemco Aero Wing used for the wings of the Poly Prop Sherry (PPS)
I also get a nagging feeling of waste when chucking away items that may have finished their original intention but are so nicely engineered it seems to be a sacrilege not to find a good alternative use for them. Such items include 35mm film cassettes. Here's a way to economise on the amount of yarn used up in tying a few flies and put those old 35mm film cassettes to good use...
Just wind the yarn onto the spool, load it back into the cassette with one end of yarn sticking out of the original light trap and there you have an ideal dispenser that saves you from wasting that little bit that is always left if you simply cut off a length to tie a few flies with. You gain the same economy that you get by using a bobbin holder for your thread.