Lay a thread base and lash a doubled length of.025 non-lead wire along the top of the shank for weight and to flip the fly point-up.
At the bend tie in six 1.5-inch sections of tan micro chenille, three per side, each with an overhand knot for a jointed leg; add two 4-inch strands doubled and knotted for the claws.
Figure-8 the crab eyes across the shank, spacing them evenly between the claws.
Invert the hook. Blend tan and brown McFlyfoam into one mottled bundle and lash it across the center of the shank with tight wraps so it flares fore and aft.
Lift the foam and make one clean scissor cut parallel to the shank, shaping a low domed shell; leave the eye stalks peeking out the front.
Saturate the thread tie-down with UV resin and cure hard, then streak the shell with tan fabric paint and taper the leg and claw tips with a lighter.