This plan came from the old Top Flite kit, which has been out of production for quite a long time now. It’s a high performance pattern type biplane with symmetrical airfoil. The short kit contains surprisingly few parts. There are fuselage sides, wing ribs, a couple of bulkheads, and the tips of the vertical and horizontal stabilizers. The stabilizers, control surfaces, and most of the fuselage framing and doublers are to be made from your own stock materials.
You have two options to consider. Choice #1: You can get the wing ribs cut for 1/4 x 3/8 hard balsa spars as shown on the plan, or 1/4 x 1/4 hardwood spars. Choice #2: You can get balsa fuselage sides as shown on the plan, or lite ply fuselage sides. The balsa fuselage side is split down the middle and needs to be joined to make a complete fuselage side. The lite ply side is cut in one piece