I'm glad you asked.
A Sonoma Shanty is a small building which measures 15 feet long, 8 feet wide and 12 feet high. It was designed by Kent Griswold and Stephen Marshall to be easily built at a low cost. Since it has a floor area of 120 square feet, it is considered a shed by most building codes.
But don't let that fool you. The Sonoma Shanty was designed to be a tiny house. It could be used as a shed, a vacation cabin or a place to live. The tiny house movement is about simplifying your life, letting go of excess possessions and living with only what you really need. One result of this is downsizing the size of your house as much as possible. Many tiny houses are in the range of 90 to 150 square feet in size. Since the majority of zoning laws in the US, prohibit building houses of this size, the tiny house movement resorted to building houses on trailers, which can be moved and thus get around the zoning laws. Two of the constraints of building a house on a trailer are that it can only have a maximum width of 8.5 feet and a maximum height of 13.5 feet, so that it can be legally towed on the road. So that is where the width and height limits of the Sonoma Shanty came from.
So what can you fit inside a tiny house? This is a typical floor plan for a Sonoma Shanty.
As you can see, there is room for a small living room, a small kitchen and a small bathroom. Sleeping arrangements usually consist of a loft over the bathroom / kitchen area for a full size mattress.
Here are some examples of Sonoma Shantys which have been built.
This is an example of a Sonoma Shanty built on a trailer. This particular version is 20 feet in length.
So where do I get plans to build a Sonoma Shanty? Kent Griswold offers the plans for sale on his website. The plans show a foundation on concrete pier blocks, but it can also be built on a trailer.