thanks for all the info guys. Is the fuel readily available in central and south America?
I have used homemade soda can alcohol stoves for years, including for 5 months hiking the Pacific Coast Trail from Mexico to Canada. I've used them as high as 18,000 feet mountain climbing in Peru, and in below freezing temps, so don't let anyone tell you that you can't use them in low temps or at high altitude. They work great, just be careful not to tip them over. If it is windy, you need a wind shield. It helps at other times as well to hold in the heat. Make sure you use a lid on your pot as well, reduces cooking time.
To try one out, just put alcohol in an empty tuna cat food can. Support the pot about an inch above that with stones or tent pegs. If you punch holes around the edge of the can, near the top, with a paper punch, you can set the pot right on the can. BUT be very careful doing this, any slight wind will blow the flames up to a foot away from the stove!
The best fuel to use in the U.S. is HEET (or other brand) gas line deicer, but make sure it is methenol (in the yellow bottle). In Peru, methenol is called metilico and costs about $5 per gallon (4 liters actually). You can also burn Ron para quemar (cooking alcohol), but it usually isn't as pure and burns much slower and cooler, especially at altitude.
Search for 'pepsi can stove' or alcohol stove on the net and you will find lots of plans for different models. Sgt. Rock has a good site, as well as others.
Here is a link to my review and information about them.
http://www.spgear.org/reviews/3374/Soda-Can-Stove.html
Vic