Well, in a backward way, you're kinda covering ground that has been covered many times before here.
This only looks like a clone/update of Shade's MagicalSketch tool, which was itself an upgrade of Teddy - first presented at Siggraph 1999. Sketch based 3D, especially as it is implemented here, is conceptually interesting. However, getting precise results with this design is pretty much impossible. The models often come out chunky & blobby. Neither of the previous 2 or 3 attempts at this design have proven to be greatly useful to anybody other than CG newbies or kids. I don't expect ShapeShop to be much different.
Nice find, but it's still really not ready for primetime, imo.