| 摘要 |
The device has three wooden main flat surfaces, plasters, cement materials, scrub materials, concrete materials, or composite materials molded, machined or injected. The flat surfaces are provided with a specific length and a specific width (2). An independent wedge is provided with a same height and a same width. Other wedges (5) are formed higher than the length and the width of the flat surfaces. A difference in height is proportional to a thickness the length and the width. Upper ends are beveled with 45 degrees similar to lower ends on opposite sides. |
