Making the original vector is the easy part and there is much more to grading and pattern making than one would think. Types of material have to be taken into consideration, the scale of the grading (1/2",1", 2", etc) and even the type and weight of the thread being used. Your best option would be to hire a pattern maker to design the initial pattern as this is what they do for a living. This can be taken from an existing pattern or a shirt that is purchased. At this time, it can be deconstructed and altered if need be. Once the initial pattern is derived, a sample needs to be made from that pattern to see how the pieces fit. Take notes and alter the pattern if necessary and make another sample. Keep doing this until your are absolutely sure that everything fits. Make sure there is no bunching and puckering and that it has a nice drape. Once that golden sample has been made, it is then time to grade. Your main sample should be a size large and from this, all of the other sizes will be determined (XS, small, medium, XL, 2XL,3XL,4XL, etc). You need to make sure that the grader can export the files to something that can be converted to a vector, such as an .eps or .ai file as they will be coming from a PC based cad program that uses SVG or DXF files. Hope this helps.