Pallets are a resource that can be recycled. Here is a cute little cabin made from pallets. I have the idea that one could build two of these facing each other only one to the side with 6' left on the front porch area. This will create a patio area in back. If the porch 6' x 6' area is closed off between the two cabins it could be a walk through bathroom with a toilet and shower. One living section could be a kitchen living area and the other section a bedroom/ storage area. Each could have a sink so wash up would be simple and since all the plumping would be in the central area of the 6' x 6' enclosed area you could have a door going outside and an ourdoor sink along the patio wall as well. Two sections of fence which could also be pallets would enclose the 10' x 10' patio area, for privacy. It could be used for gardening and have sliding glass doors leading from the kitchen living area.
Pallets can be purchased by the truckload for about $2.00 each or gathered for free from local sources.