Assembled inner rib and stringer section and then riveted it all to the forward spar. Had to buck all of the rivets since the squeezer couldn't get around the spar flange. Need one of the longeron yokes for the squeezer at some point. Dropped the rear spar and rib skeleton into the skins. As I cleco'd the spar in place I realized that I skipped the riveting of two of the forward ribs. That would have been a disaster. Pulled the skeleton back and out and bucked those remaining front rib rivets - some of my best work actually. Put the skeleton into the skins a second time and double check everything as I cleco'd it in place. Squeezed the -4 rivets from the spar to the front ribs on the ends and installed the blind rivets on the remaining ribs. I messed up though and mistakenly installed blind rivets into the holes for the main ribs, not the forward ribs. My first attempt at drilling out LP4-3 blind rivets. Pretty easy actually, just used one of the discarded mandrels to drive out the rivet and then drilled it out with a 1/8” bit. Installed the remaining main ribs, squeezing the outboard -4s and then correctly installed the blind rivets in the inboard rib. Stopped short of starting the skin riveting. That's going to be quite a chore.