This short kit includes multiple layers of 1/8″ plywood to be laminated to make the cabane struts, which are shown on the plan as 1/4″ spruce. It’s the builder’s choice, so build it whichever way you like. I’m also including a floor to be set into the top of the cabane struts. (You can see this modification in the photos of the Sporty Forty biplane.) This allows you to bolt the wing on from the top, through the cabane floor, with nylon bolts and blind nuts. If you choose this method for attaching the top wing, reinforce the joint between the strut and the floor with triangle stock. Naturally, you can ignore this part and build the plane as shown on the plan instead.