A three-dimensional wood fiber structural composite comprises a uniformly strong three-dimensional wood fiber structural core and thin face plies securely laminated on top and bottom contacting surfaces of the wood fiber structural core, wherein the core has a depth in the vertical axis of up to about 1\xbd\u2033 to 1\xbe\u2033. The chassis includes a first body, a second body, and an electromagnetic shield coupled between the first body and the second body. The device for reversing the blood flow for an extracorporeal blood treatment device includes two valve bodies which are rotated relative to one another for reversing the blood flow. A second abrasive grain slurry is supplied to a part of an area where the saw wire meshes with the workpiece. The method also involves sterilizing the body.