It is taking me about 90 minutes per rib. I've done 3 now. I'll include photos of tips I'm learning. I'm riveting with the tank in its stand vertically, not horizontal. I have it fastened to the cradle and workbench so it doesn't move. I put rivet tape on the flush rivet set. I'm using tweezers to pickup and put rivets in the holes because I'm wearing rubber gloves and they are not to nimble.