Often times the homemade tools we find are more interesting than the actual tools they are meant to mimic. Such is the case with a rotary tool design that is powered by the suction of a vacuum and has the secondary effect of cleaning up after itself.
The homemade tool uses a few 3D printed parts to form a two-stage axial turbine that transfers rotation to a center shaft that holds the rotary bits. Most of the tool is 3D printed, except for the bearings and the shaft. The shaft actually seems to be the hard part because of the tricky threads that are required to use the Dremel collet and nut.
The designer calculated that his vac powered rotary tool spins at 60,000 RPM—a typical electric rotary tool spins at around 35,000 RPM, so it is probably best to use with extreme caution. A variable speed dust extractor might be the better way to go. Not only does the vacuum power the tool, but it also sucks up the dust while you are cutting. The tool has its pluses, but I imagine being attached to a stiff vacuum hose could be a problem
