Sanded and prepared all spars for application of plywood faces. Drilled 1/8" hole in center of all vertical pieces to allow for pressure equalization between bays. Scrafed 4x4 ft sections of 2.5mm plywood that will be used on all spar faces. Grain of plywood needs to run perpendicular to spar which required scrafing the plywood pieces together. However, not easy to scarf plywood going with grain and would probably cut smaller pieces (2'x2') if done again. Epoxied plywood web face to center spar. Used extra epoxy (T-88) to make sure all areas covered well.