Layout the two halves that will become the saw handle. The handle halves should be long enough to fit your hand (with winter gloves on), and about 1/8th of an inch wider than the width of your blade on the handle end.
Cut the two handle halves from 1/4-inch thick stock (plywood in this case) on your saw from.
Center them over the two handle holes on the blade, and drill the fastener holes through the handle halves.
Align the two handle halves together, and temporarily bolt them together with the binding posts (do not have the saw blade in the middle at this point).
With the handle temporarily assembled, sand the handle to even up the front and back edges (the other edges are sanded later).
Unfasten the paddles.