This technique isn't anything new, but it definitely has a place in capturing R.O.B. from his original pieces. With a scanner handy, I took copy of the inside of R.O.B.'s left arm and imported the image into Solidworks. From here (or with any vector program, like Inkscape) I can capture some of the relative distances between features and scale to a known dimension. There are some caveats to this technique: for example, the scanner really only reveals distances for features at a constant height away from the scanner. For this reason, capturing flat features is my primary use for this technique. Furthermore, I wouldn't use this technique for 0.001" accuracy, but in this case, it's good enough.
If you have a CNC (or manual) milling machine nearby, you have the option of a similar (and far more accurate) technique than this one here: you can simply clamp your part into the vice and index all of your features by moving the mill head to each feature with a tool like an edge-finder.