[throwup238]

> The drawing & modelling are not the difficult bit - the CAM programming is.

Actually the drawing and modeling are very much the hard part, so much so that the open source geometric kernels are decades behind the commercial ones. The computational geometry is genuinely a hard problem due to floating point errors and degenerate cases like parallel surfaces and tangent lines.

Once you have the geometric kernels, CAM is little more than a physically aware pathfinding optimization problem. Computationally expensive but otherwise straight forward. The kernel, on the other hand, has to be built up experimentally, tracking down every place where the math breaks down or there’s a pathological case, until you’ve got the thousands of special cases worked out.