Says who? I'm satisfied with the sum of replies.

Even if that's true for somebody, that's certainly not true for everybody. I BUILD and USE my own designs. Anyone who BUILDS their own designs becomes very familiar with the need to design things right. The devil is in the details. Just amazing how many revisions one can go through before actually feeling good about building it. That's especially true if you want to reduce work (lazy), and if efficiency is one's primary concern. I recently came up with a flats and slots cutter. Very accurate for the low cost. I immediately used it and the results are fantastic. I needed it for way too many years before figuring out the easy way to make such a jig. Now I can make couplings between my motor and bike, and did. It's accurate to within a few hundredths of a millimeter, from one square drive edge-to-edge compared to the other pair of edges.