Floatation should not be an issue. Golden stone shown here; change size and color to suit your local emergence.
hook - Dai Riki 280 #8
thread - UTC 140 tan
egg sac - 2mm foam black
body - 1mm foam tan
body hackle - ginger (undersize by 2)
rib - x-fine wire gold
binder strip - 2mm x 2mm foam
wing - yearling elk
legs - medium rubber barred tan
thorax - Ice Dub golden brown
front hackle - grizzly
Part 1
insert needle in vise, then black foam on the needle; start thread
fold foam forward; 2 soft loops (so the foam isn't cut), pull tight and create first segment
pull foam back, move thread forward on needle
create next segment; repeat, repeat, repeat, then cover with thread to create underbody
tie in tan foam, tie in rib