I just saw this on reddit, the proyects posted here are intimidating :/
I'm not an architect, I don't have any design tools at hand, all I have is some paper a pen and this computer and almost no time to work on this proyect, but I wanted to help by providing another idea, there are no bad ideas just bad ways to present them... and this one is really bad, but it's the only one I have at hand.
The idea of the proyect is to use less materials as posible and a lot of hard work. Basically is a simple wooden structure and a hole in the ground.
First the hole has be digged, this will give the general shape of the house, then just use some wooden poles to raise the height of the house. Then just install something that may suit as a roof like a PVC roof or wood.
I almost feel shame on me by posting this :/ anyhow I will do it.