PURPOSE: To simplify a painting process and obtain a highgrade sense as high as a conventional ginkgo nut-shaped face by providing steps at the respective edges of the faces and chamfering the crossing parts of the steps.

CONSTITUTION: Steps 3 are shaped at the edges of respective faces 1, 2 and the crossings are chamfered to form slopes 4. The steps 3 can be shaped with a plane, a router, a chamfering tool, etc., and the depth D and the width W thereof are 1-5mm and 3-20mm, respectively. The chamfering can be done by a plane, a router, a chamfering tool, etc. The chamfered angle θ is usually 30°-60°, by 45° as a standard. Although the obtained edges are constituted of only planes, acute angles are removed remarkably after painting and a highgrade sense as high as a conventional ginkgo nut-shaped face can be obtained.