ok ive got a new problem when scaling my upper arm the length is 8 inch which is 203 mm. but my width is 16inch which is 407 mm. now i cant scale them sepreatly without the others changing. help
You can't adjust one without the other adjusting. My advice is to build it to the lenght of your arm and adjust the width after you have the paper model built. That might mean adding paper where needed to make it fit.