Beaver stab
You build the beaver stab upside down. The reason is, so that when you hinge the elev to it , all the hinges are along a straight line( so it doesn't bind )...The center part of the stab is around 3/4" and as you work out to the tip it becomes 3/8" there's your taper....I'll see if I can take some photos ,got to borrow a digi cam...