This is a model of the footprint of a TO-3 transistor package. It can for instance be used as a jig for drilling holes into a heat sink.The default parameters adhere to the standard TO-3 footprint, but you can change any parameter you like (e.g. width, depth, height, size of the holes, distance between holes, etc.). For instance, you might want to enlarge the hole sizes in order to use this model as a jig for drilling holes in a heat sink. Just look at the OpenSCAD file, all parameters are listed at the top...