Clecoed bottom skin from rear to front, checked for clearance around aileron and flap hinge arms. When we made it to the front spar with clecos I double checked for square, used the vise-grip adapted forming tool to place a very slight turned down edge on the leading edge of the lower wing skin. Then, match drilled the #40 holes in the skin out to #30 while simultaneously going through the leading edge/spar. Started in middle and clecoed every other hole as I worked out. When done with drilling I deburred the skin holes and then used a 120 degree dimple dies in squeezer to dimple the front edge of the lower skin. Next I used a 120 degree countersink bit in a cage to countersink the leading edge/forward spar to accept the dimpled skin and countersink rivets. Pictures not in order