These guys have a set of templates you can send off to a rapid prototyper (or yourself) to build a kit-set for your own cathedral. You choose which sections you want printed

Then glue them together yourself -

This is what procedural architecture is all about - what they have here is a simple shape grammar! We're not far from the situation of having designs where you can define an arbitrary floor plan and style on a website, and download a solid file you can get printed. Or how about having it printed big enough to be a dog house? or somewhere to live in the summer? I can't wait for the first lorry to arrive with a procedurally generated building on the back :)