I made a press. Basically, there were 5 pieces of wood, each the same height as another except for the tallest in the middle so it went Small, med, tall, med, small. Tallest was 4in and the shortest was 3 and 1/2in. That way it gave it a 1/2in posotive camber lenght wise. I gave it some negative camber width wise by cutting the same curve away from each piece. Basically just drew a center line then marked a point 1/2in dotwn from the top and traced a curved line connecting the three points (both top corners and the center point).