use this technique in order to emphasize the contour of the object. To do it you have to entwine two warp threads (front and back) with the working thread. To make a contour we usually use thicker threads.
Weaving techniques that might be helpful (not for card weaving but for weaving where the warp threads are spaced further apart. This board is very useful for details about weaving. (For stories about Peruvian children and adults weaving