Nowadays there are a lot of foam based floating fry around, the patterns haven't changed much since the old patterns of 40 years ago, most of the new foam fry just feature more foam and maybe a fritz chenille or similar instead of mylar tubing for the underbody. What you don't see around so much are deer hair floating fry, the reason should be pretty obvious; foam is much quicker and easier than deer hair. But it's not as good. There's something about the way a spun deer hair body sits in the water's that just imitates a stunned fry so much better than a wedge of foam, especially when you've squeezed the back end to get some water in the hair. Years ago a friend and I ran tests over several days-the only difference in set ups was the fly, and we swapped rods twice each day to make things as fair as possible. The deer hair fry consistently out performed the foam, there were days where it was close, but no days where the deer hair fry was getting refusals while the foam fry was getting eaten. The foam fry always got more aborted takes and refusals. Also the deer hair fry is easier for the fish to eat as it only has a soft marabou or rabbit hair tail extending behind the hook bend, unlike most foam patterns which have a tail of thick foam extending back-often a shank length- behind the bend. So even the fish that want to eat the foam fry sometimes fail to because the buoyancy and the stiff tail pushes the fly to safety. I don't remember the exact numbers, but it accounted for a consderable difference in fish numbers over the few weeks of fry feeding. When a lot of those fish are fin perfect browns in the 3-5lb bracket that matters. it certainly matters enough to warrant the extra time at the vice.
If you do fish for fry feeding trout, tie some deer hair fry for the surface and keep the foam for the popping fry and booby minkies. It's worth the effort.
3X longshank streamer hook 2-6
Thread: GSP 100
Tail: Marabou or rabbit
Body: White deer belly hair spun and clipped to shape -don't pack it too tight
Tape eyes and marker pens