Cost to build this tiny house was $3500 for materials, labor was donated by my non-profit. This tiny house follows the guidelines of AB 2176 for "housing crisis emergency shelter". Having 120 square feet and being no taller than 15 ft above ground level, no permits are required. As part of a workaround for dealing with occupancy issues, zoning laws and unpleasant nimby neighbors in Marin County, it is located on a "sanctuary site" - where federal religious land use laws apply under RLUIPA.
This tiny house provides shelter for a young couple who grew up in Marin, obtained college degrees and are both employed in Marin. After a series of rent increases on a small room they were renting which was substandard, they could not find any other affordable options in Marin and started living out of a car.
The plans are open source - I am working on completing a sketchup model before the plans go up on github. Since my non-profit wishes to construct more of these shelters in Marin and other locations in California, I am working on the next version of the design which incorporates elements from wikihouse and will utilize a cnc router for construction.