I've been experimenting with designing parts for 3d printing and the results have been encouraging. Now I have a problem though. It's easy enough to design a part with a ball that goes into an existing socket or a mushroom peg that goes into an existing port: you just get the measurements and make a ball or disc the right size. But what if I want a part that follows a more complex contour of an existing part? How can I get that three dimensional contour into my 3d design program so I can design a part that follows it and fits nicely with the existing piece? If it helps, I'm specifically thinking of the irregular shaped hole in the back of Wei Jiang Arcee's thighs and the collar piece. I can probably get the collar close enough by just importing a decent photo and taking measurements but I doubt I'd be able to get a good fit using that technique on the thighs.