Overbody Clear head cement (strip of anti-static bag)
Underbody Opal material (medium Mirage tinsel, coloured red with a Sharpie)
Finish (UV resin)
How to tie it
Tie the white Antron gills in first, right behind the eye with the bead pushed back. A couple of wraps over, a few in front to prop them up, then whip finish and cut off. Doing the gills first lets the bead slide forward and bury all the butts.
Slide the bead up, reattach the thread over the gill tie-in and tie in small red ultra wire down into the bend.
Trim the anti-static bag strip to a point before tying it in at the rear. That taper is what stops a bulky lump at the back of a very slim fly.
Tie the medium opal Mirage tinsel in near the front rather than at the bend so the rear of the fly stays thin, then build your thread taper and wind the tinsel forward in flat, non-overlapping turns.
Colour the wrapped tinsel with a red Sharpie. You do not need perfect coverage, then wind the anti-static bag over the top in touching turns so the red mylar glows through as a bloody, gassy body.
Rib with the red wire, helicopter it off, whip finish, trim the gills, then spread UV resin over the body with a bodkin. The resin is what makes the colours underneath really pop, so keep the coat thin and even.