The elevator of the Aeronca has a very narrow connection between the left and right side. If the elevator is being built with balsa and hardwoods there would be no concern about connecting the halves. But foam board does not have the torsional strength of balsa in this application. An exact foam replica from the plan would give a very narrow strip of foam board to connect the halves. So I decided to add a joiner made from 3/16″ x 1/2″ firm balsa. The middle pic shows what that looks like. Next is the need to cut a 45° bevel on the leading edge of the elevator. Normally cutting a bevel in foam board is easy, but with the addition of the balsa joiner the task becomes more challenging. Two possible ways to make a bevel in the balsa. One is to file or sand the bevel in the balsa before gluing it in to the foam board. Another is to use a power tool. I used a Microlux table saw. Just set the fence and make the cut. Comes in very handy.