Wlofie [1] directed me towards the Hirst Arts Fantasy Architecture [2] which allows you to build your own miniature castles (primarily for role playing games, but used for other reasons [3] as well).
The whole site excites me on two levels.
One level, that of going out, buying molds [4], plaster of paris, some glue, and going to town making cathedral [5] or two.
And on the second level, the sheer amount of information given on the site on model building. Not only the number of projects [6] you can make, but tips [7] to help the building process and instructional videos [8] on the various techniques used to build the models. And even more great (given that the company just sells the molds) are how the molds are made [9], with instructions on making your own molds.
That, I really like. Bruce Hirst [10] (owner of the two person company) is not afraid of telling you how he makes the molds. Given the time and complexity I'm sure it's easier and cheaper to buy the molds from him, but still—the fact that he goes into such depth on how he makes them is very neat. The site is well worth the few hours it'll take to go over everything.
[1] http://wlofie.dyndns.org/diary/2006/07/11/152926.shtml
[3] http://www.hirstarts.com/gallery/gallery.html
[4] http://www.hirstarts.com/molds/molds.html
[5] http://www.hirstarts.com/cathed/cathed.html
[6] http://www.hirstarts.com/projects.html
[7] http://www.hirstarts.com/tipsmain/tipsmain.html
[8] http://www.hirstarts.com/video/video.html
[9] http://www.hirstarts.com/moldmake/moldmaking.html