Hay @orm glad to hear you are working on a Rocket stove. I hope it will pay out for itself if you video it 3D print :). Simulate it here https://www.simscale.com/

You can use Rammed earth as well http://rammedearth.blogspot.ae/2013/09/rammed-earth-cookstove-in-chad.html

If you want to build a Vaulted ceiling here are my quick links and inspiration.

http://web.mit.edu/cron/Backup/project/guastavino/www/about.html
http://umanitoba.ca/faculties/architecture/facilities/cast.html
http://makezine.com/2009/06/30/lost-knowledge-timbrel-vaulting/
http://www.lowtechmagazine.com/2008/11/tiles-vaults.html
http://www.treehugger.com/green-architecture/classic-timbrel-vaults-built-computers-and-3d-routers-reinventing-minimalist-technology.html
http://www.treehugger.com/sustainable-product-design/crossway-zero-carbon-home-brings-back-the-timbrel-vault.html