Giorgos from PCBheaven has been working on a DIY hot-air gun NC machine and wrote a detailed explanation on his blog describing the build:
Four pieces is all it takes to make the frame of the NC. And BTW, an NC machine is the same as a CNC without the leading C. CNC stands for “Computer Numerical Control” and NC stands for just “Numerical Control”. My device will follow “numbers” to go into specific positions, but there is n o computer or CAD/CAM software whatsoever, so it is an NC machine…