Well, you should avoid wood that has an odor, like pine, snadalwood, cedar...
Any wood that you get from someplace other than the pet store ought to be boiled with a few changes of water, so particle board (or anything else with glue in it, for that matter) is definitely out too.
I'd be more concerned about the glue. What are you going to use? aquarium silicone? Gets a little stringy for model work, doesn't it?
I hear hot glue may be Ok, but that's a little thick too, isn't it? you may want to experiment with just any old stuff to see if the glue will be OK before you get too worried about what kind of wood to use.