I will take mylar (pearl) indiviual strips; I pull apart the mylar,
& tie in 2 or three (depending on nymph size).
I coat the flash back with a light coat of superglue. The chemical reaction of the superglue on the mylar strips sets off some amazing color, & really entices the trout. You can see this on the Conejos Olive Flashback Nymph I have pictured with recipe on Flytyingworld.com