Fitted all stiffeners and longerons. Match drilled upper and lower longerons. Lower longerons countersunk using a .020 inch shim and countersinking tool on hand drill. Difficulty getting accurate depths because of the step on the lower longeron. Might have been better on the drill press with a jig but satisfactory. Dimpled both skins on the table. Dimpled all stiffeners with hand squeezer. Reassembled with Cleco‘s and riveted with BSC 42 and BSC 43 rivets as specified. Side skins completed.