I like what you all are coming up with! I have a thought about these flies, though--why not get the big foam--eyes? boobies?--up at the bend of the hook, behind the claws, instead of at the eye of the hook? More flotation at the front (claw end) would help keep the hook point up and reduce snags--though @Freestone avoids this with the inverted hook. And while they don't realistically represent eyes, they kind of give that impression, and the eyes of the natural are up front. (Touching them up with a black marker might not hurt, though the bright color in @Buzzy's also makes a hotspot.) Lastly, a fleeing crayfish has claws up and tail down (curled under) while scooting backwards. Elevating the tail end is pretty much the opposite of the natural.