I’ve made few physical vault models for teaching purposes, barrell and cross vault.
Idea is to show how do they work, eg. how they must be built in order to stay up. Anyway, here is the model:
http://www.opendimension.org/blender_en/blends/vaults.blend
EDIT. I forgot to mention that these will collapse with 2.45. I’ve used SVN version and they should stay up fine.
Feel free to use for your own purposes.
PS. My previous arch pressure models can be found here:
http://www.opendimension.org/blender_en/arch_pressure.php