First, with a heat gun, you can straighten out some or all of the curve on a fiberglass fuse. I don't go to the extreme care of some, Because I figure some of it cancels out in the air ie: slightly different airfoils, leading edge radius, wing weight, wing area, aileron area, it all varies side to side, as these planes are hand built. If your within +/- 1/16 or 1/8 on squareness, I'll guarantee you cannot tell in the air. I use my pool table and I have four vernier stands. So I use one to make the stab perpendicular to the table. Then I set the elevator on two stands, one on each end to hold it level, THen, I walk to the end of the room to see if it looks right. It's easy to make a mistake measuring, but if you'll look straight down the front of the plane, you can tell if the elevator and rudder are perpendicular to each other. Actualy on this and on the wing to stab relationship, visual can be almost dead nts. Anyway, I then epoxy the fin to the fuse and let it sit overnight. I do the same with the wing. If it's two piece, I slip the wings on and align, not just align the wingtube, because sometimes I find the wing tube is not identical on both wings.