Mount the 3x hook and wrap lead wire heavily along the full shank; overwrap with thread to lock it and taper the ends.
At the bend tie in two short black biots splayed into a fork as the twin tails.
Tie in the Thin Skin strip for the shellback, a length of ribbing thread, and a black hen hackle by the tip; then dub a segmented black-brown body two-thirds up the shank.
Palmer the hen hackle forward through the body in open turns for the legs, then trim the fibres off the top and bottom so they sweep out to the sides only.
Pull the Thin Skin over the back to form the shellback and rib forward over it with the ribbing to lock the segments; tie off and snip.
Finish the head area, then tie in two more black biots at the front splayed forward as the pincers.