Check out these photos of a paper craft of Howl's Moving Castle. Groovy.
There were actually a number of books in Japan where you could construct your own replica of Howl's Castle. Also, if you don't mind losing the color, you can download templates and print them off of your computer. Just give it the 'ol Google try and see what you come up with. Or you can just check out this person's blog (see the links on the pics) and he should be able to help you. Good luck!