Abstract: A sewing machine attachment and method for use in connection with multiple thread sewing machines to provide selective control of decorative stitch formation to selectively vary either pattern amplitude, or frequency of pattern repeat or both. A selectively adjustable variable speed drive is employed to drive a cam shaft carrying a plurality of selectively adjustable cams one for each thread forming the pattern which cams bear against a plunger acting to control the position of the selectively adjustable pressure plates forming the thread tensioners through which the threads of the machine are guided. By varying either speed and/or cam position and/or thread tensioner plate pressure different stitch formation can be obtained.