The stiffeners come 2 per angle section. Each needs to be cut from as shown on the drawing. I studied the drawing for a while, and didn't seen anything peculiar so I started cutting out the pieces.
After cutting each piece from the angle stock, they need to be cut to length depending on where they are installed on the skin. This didn't take long, and I started to file and deburr the first stiffeners. I only did the first 2 before quitting for the night.