TECHNOLOGY FOCUS - METALLURGY - Preferred Method: The wavy shapes may propagate in two different directions: the waves of short wave-lengths resembling the channel contour of the metal plate to be formed propagate perpendicularly to the channel-length direction, while superimposing the waves of longer wave-lengths which propagate in the channel-length direction. For relatively simple plate designs with primarily straight channels of moderate forming difficulties in the active area, at a channel-depth to sheet-metal-thickness ratio of 3 or less, the wavy shapes are provided with a ratio of peak-to-valley-amplitude to sheet-metal-thickness of 0.1 to 0.4. For relatively simple plate designs with primarily straight channels of very high forming difficulties, at a channel-depth to sheet-metal-thickness ratio of 4 or more, the wavy shapes are provided with a ratio of peak-to-valley-amplitude to sheet-metal-thickness of 1.0 to 4.0. For relatively complex plate designs with multiple curvatures and of moderate to high forming difficulties, at a channel-depth to sheet-metal-thickness ratio of 3 to 4, short waves or smoothly connected, round-shaped hills and valleys are provided with a ratio of peak-to-valley-amplitude to sheet-metal-thickness of 0.4 to 1.0. For complex plate designs with multiple curvatures and of very high forming difficulties, the wavy shapes are provided to resemble the channel and feature contours of the metal plate to be formed, while the texturing process may have to be carried out at a lower speed than that at a metal mill, using a method similar to a progressive die process. The wavy shapes are provided with the short wave-lengths (in the direction perpendicular to the channel-length direction) equal to or substantially close to the channel pitches in the active area of the metal plate to be formed. The wavy shapes are provided with the longer wave-lengths (in the channel-length direction) which depend on the feature contour in the transition and port areas of the metal plate to be formed. Texturing may be carried out at a metal mill during the final rolling stage for high-speed processing.