Start Nano Silk 12/0 at the halfway point of a size 4 10XL streamer hook and set a calf tail tail with the tips just past the bend, binding back until the thread is level with the point. Trimming the butts on a taper before you tie in stops a step forming under the body.
Move forward, leaving a space behind the eye, and set an equal clump of calf tail as the forward wing, the same length as the tail. Cement both and let it dry hard. Everything after this gets packed and trimmed, and loose anchors will fail.
Cage the tail and wing under wire wraps so they stay out of the way while you work. On a body over two inches long this is the difference between a clean fly and a butchered one.
Tie two folded brown grizzly saddles in by their tips from underneath at the base of the tail and secure them under the wire too. Set now, palmered at the very end.
Spin deer hair from the tail base forward to the wing, roughly pencil-diameter clumps, compressing each one hard with a brassie before adding the next. Density is what makes a bomber float through a whole run of fast water.
Trim the body: long curved scissors first to take the bulk off, then straight scissors for the taper away from the tail, then a razor blade to finish. Work from bulk to detail or you will cut a flat spot you cannot fix.
Free the hackles, palmer both forward through the deer hair on a slight angle and tie them off around the wing, then add a third folded hackle in the space between body and wing and wind it edge to edge. Whip finish, cement and brush the hackle out.