Awesome stuff!
I wish I had the time, always wanted to build my own CSG (Constructive Solid Geometry) engine (like the ACIS modeler), a lot of the stuff you're doing is closely/directly related. I've dabbled and made a few starts with a bit of help from a book (will dig it out) and just dig a quick search and there's a lot more info out there now on the topic.
Good stuff, it's pretty heavy going math wise
