Often encounter such a situation, some client only  provide a picture and 2d drawings, asked to do what is the price of the model .If only a picture, it is difficult to quote accurate price, it is not the corresponding material;The second is no specific size data.There are 2 d drawings also slightly better, at least be able to see the relevant data, but this kind of situation can only offer not to do, if you want to make a mockup, you need to provide a  3 d drawings,such as STEP IGS X-T.

The reason why need the 3d draiwngs because  is the one of the steps for make  programming, need to use 3 d drawings, in general, the format files  is  STP, is made of proE program, in addition, igs, x_t, PRT drawings can also do these formats;If you need to do 3 d printing prototype, the need for the drawing of the STL format.No matter what, provide the STP format drawings is better