Positioned and drilled stiffeners to skin. Discovered that I had trimmed and drilled holes on the wrong side per plans. Had to remark one side of elevator skin and move lines 1/4." Drilled stiffeners to other side of skin. Dimpled and deburred all holes in stiffeners. Deburred all holes in skin and peeled adhesive off exterior of skin along rivet lines. Using C-shaped dimpler, dimpled all holes in skin except for holes closest to trailing edge. Dimpled some holes using pop-rivet gun and dimple dies.