Put a #12 nymph hook in the vise with the shank level, wrap a section of lead wire around the shank, and break/twist it tight to form a weighted underbody.
Start black thread, build a thread dam at each end of the lead to lock it in place, and trim the tag.
Tie in four or five peacock herls by the tips at the back of the lead with four or five tight wraps, then trim the tag ends.
Rope the herl together with the tying thread by twisting them into a single strand so it resists breaking.
Wrap the roped herl forward in tight turns, covering the lead, up to about one eye-width behind the eye; rope more herl if you run out.
Clip the herl and take several wraps behind the eye to form a small head.