What the Mennonites were doing for the hurricane relief recipients were basic wood "shells." You would not want to build a structure like this if you are building a house in Belize, as it is not hurricane resistant. Those structures were built for Mayan villagers who had no homes at all after Iris and needed something put up quick.
If you don't want to go the cement-block route, there are several companies that are building synthetic prefab house components that are easy to use, quicker to erect (thus labor costs are lower) and can be made hurricane resistant if done the right way. The best known one is Covintec, a Mexican product (www.covintec.com
There is a company in Australia that makes high quality hurricane resistant prefab homes that are very attractive. They are pricey though, especially in Belize because of the customs duties (not sure what they are on this stuff). It's Force-10 (I think its www.force-10.com
but do a google search if it isn't.)
I suggest you visit the Millennial House web site (not sure of URL, do a google search) and look at all the cement block alternatives. Another one is Eco-Block.
Google searches will find all these for you.
We were going to use this for a house in Belize but we decided to build in Panama instead and are using local hardwoods as its below the hurricane belt and much cheaper and simpler than what we had planned for Belize.