We used to make fine looking control line models that way in the late 40' and 50's. There is a modeling blade available from Micro Mark and others that is a circle that fits in the large handle of a hobby knife. We used to make a U shape of the fuselage, attach a suitable balsa block and shape to the contour wanted and then remove and hollow to a satisfactory thickness. Top of the foward fuselage the same way. Cowling can also be made in this manner. The weight will depend on the balsa you use. The biggest advantage is there are no sheeting lines or gaps.