I have been working with a lot of cow poo here. After originally thinking touching fresh poo in order to make a fuel efficient stove at a migrant camp was gross enough, I spent all weekend shoveling 4 day old poo into a bio gas fuel plant and my opinion quickly changed. Making stoves out of poo now seems like a tea party compared to the ridiculous labor I did this past weekend - I would prefer never to have to be that covered in cow dung ever again in my life.