Oliver (Prof. Henry)
I would cut a pattern out of 1/2" mdf or plywood to use with a pattern bit in the router. You could use your jig saw to cut the pattern by cutting about 1/8" outside the line of your drawing and then sanding to the line to make sure you have a smooth edge. Cut your final pieces the same way (leaving the 1/8" excess) and then use the pattern you made to rout them to final size. The bearing on the pattern bit follows the curve of your pattern to give you a smooth, accurate final shape.