Honestly, this is a quite complicated part. If I were you, I'd use a handheld 3D scanner. Not perfect, but it'll do the job. http://us.xyzprinting.com/us_en/Product/3D-Scanner?gclid=CjwKEAjwj6PKBRCAy9-07PeTtGgSJAC1P9xGw8z56fJv9YsbfftIyPkfbby_ffJJ5lGrek6zFN8RMBoCkoDw_wcB
This one is a pretty good one for beginners.
i already have one. but i want to make it by some simple methodolgy