The exact shape of the blade near the root (the inner part beside the hub) is not critical. If your wood is not thick enough to achieve the listed 'drop' or thickness, you can either glue and extra piece onto it or you can simplify the design without significant loss of performance so that it fits your wood. Follow the dimensions for the outer part of the blade with care but the inner part can be adapted so long as all 3 blades are the same.