2. Before you cut the arc in the front and back that will be the roofline, determine how high the sides will be. Measure the long side of one of the side pieces and add the thickness of the bottom board. Mark this distance up from the bottom on each edge of the front piece. Using a compass or even the edge of a dinner plate, draw an arch that curves between these two marks. Repeat on the back piece. For the curved roof, cut the curve on the front and back of the house with a jigsaw. For a peaked roof, use a hand saw to make the angled cuts of the roofline.