Start the thin white 10/0 thread on the hook shank at the point where you want the wing post, and measure a bunch of wood-duck flank fibers about one shank length. Transfer the measurement rearward, pulling up and toward you as you wrap so the fibers land right on top of the shank, then wrap back forward to the tie-in point.
Bind one end of the white polypropylene floating yarn down with tight rearward wraps and snip the short end off at an angle to leave a ramp down to the shank. Twist the yarn up hard and fold it over on itself — furled like a cinnamon twist, the post has structure, keeps itself contained, and being locked down front and back it will not spin round the slippery shank.
Have the tools ready before starting the body: two colors of rabbit-fur dubbing pulled out in clumps, a dubbing whirl, and plunger-style hackle pliers.
Lay one slender noodle of the tan and one of the brown dubbing onto the thread, form the loop, insert the dubbing whirl at the bottom and give the whole thing a good spin — the two noodles twist into a single multicolored rope.
Take a couple of wraps of the rope around the hook with the plunger hackle pliers and snip the whirl off, so you can wrap with the pliers rather than the heavy whirl.
Go back to the base of the tail with the rope and wrap forward to just in front of the post, then move the tying thread forward and lock it off. The rope gives the mottled color, natural segmentation, and real strength.
Make a single very thin noodle of the brown dubbing and use it to fill in a slightly bulbous, darker thorax right around the wing post — the natural is built that way.
Select one appropriately sized feather from each of the two capes (a natural ginger and a grizzly dun), shiny sides both facing you. Strip the lower fuzzy fibers from both feathers at once, then strip a little more from just the top edges of each.
Lay the two stems across the front of the post and wrap the thread up the post over them and all the way back down — the furled post plus the two stems give enough structure that you do not have to grip the post — then snip the stem butts off. Leave the thread on the near side in front of the post.
Rotate the vise about 90 degrees and wrap both feathers together up the post, behind the hanging tying thread. Pulling against the weight of the bobbin sandwiches the two feathers tight together for the mottled collar, and wrapping up the post with the cup of the feather down leaves the barb tips pointing down and the underbody completely clean — no thread wraps, no fibers obscuring the eye.
Whip finish, seat the knot well, and cut the tying thread free; flip the fly back to its normal orientation and snip off any wonky fibers standing up.
Trim the post about one shank tall and add one single drop of Sally Hansen Hard-as-Nails to the thread wraps. It seals the wraps and, more importantly, cements the delicate hackle stems to the post so the fly does not blow up under aggressive false casting.