Worked on spars today. Calls for 1/2 x 3/8 hardwood for the wing spars, top and bottom, that tap[er to about 5/16 at the tip rib. That's a lot of weight, and I don't have any hard wood stock in those dimensions. So....... I am making my own laminates. I am using 2 pieces of 1/4 x 3/8 balsa. I am laminating them together, with a strip of carbon fibre in between. Makes for really stiff spars, that are 1/2 the weight of the hardwood.
And easier to taper.