Used my scrap aft wing spars as a straightedge for laying out the turtledeck skin.
Used a piece of stencil board to figure out how wide the turtledeck skin would be on the big end. 
Still figuring out the size of the skin. Only had a limited amount of .020" 2024 left over from the aileron sheet.
Hard to see here. Turtledeck skin is cut out and I put a 90 degree angle on each edge with my homemade brake. Couldn't figure out how to put in the "Z" bend in as a stiffener so I rivetted a piece of hat section on each edge. 
Positioning turtledeck skin to set-up the mounting points. 
Used racheting straps to hold turtledeck in position. 
Skin aligned. Used straps to hold it straight on the sides. 