I'm sure I'll get excommunicated for this comment, BUT.... why not just buy a pack of Berkley Trout Worms in your favorite color and stop BSing around? They're already the right size, many colors, fish love them, tastes great, less filling, very durable, etc. I've got nothing against fishing with a plastic worm. Making a plastic worm and fishing it on your fly rod as some sort of feel-good measure is silly. There are also "power nymphs" and "power crickets" and other fun stuff.