Lay a thread base well around the bend - the body on this fly extends noticeably back.
Catch in the Vinyl D-rib well forward with the flat side against the hook and bind it back to the rear of the body. Test one wrap: the round side should face out, so flip it if it doesn't.
Wax the thread and dub the Coyote fur dubbing blend: take the first wrap or two at the rear, then pull the noodle tighter, spin it, and wrap forward. A slight taper looks better if you can get one; add a thin noodle and go back over it if you need more.
Counter-wrap the D-rib forward in about four evenly spaced turns (on a size 12) and bind it down with tight thread wraps - the vinyl has some stretch, so it locks in without a reverse-wrap trick.
Smooth out the tie-down lump with thread so the head area stays clean.
Prepare a small Partridge feather with a notch as its tie-in point, tie it in, and snip off the tip.
Take the feather in hackle pliers and wrap two turns; secure with two thread wraps and snip the butt.
Pull the hackle fibers back, build a decent-sized nymph head right back to the eye, smooth it out, and whip finish.
Put a small drop of UV resin over the head wraps and cure.