When I built the right leading edge, I inadvertently left out one skin to rib rivet. When I found it (after riveting the leading edge to the spar), I put a cleco in it so I wouldn't forget it. Today, I got tired of seeing that one cleco sticking out, so I set a rivet in the hole. Being the aftmost rivet in the rib, I got my tungsten bar in the spar lightening hole and was able to hold it with my fingers without having to squeeze my whole hand through. I checked the shop head with a flashlight and mirror, and all is well.