Concept
Shelter is essential and a house is a defining asset, but for the very poor, any material advantage has got to allow for incremental acquisition, serve multiple ends, and enable a radical variety of unanticipated uses.
We scale into the challenge thus:
What $20 invention would alter the landscape of both low-cost housing, and the means for attaining it?
While a basic dwelling can take many forms, there are structural, organizational and aggregational advantages to a rectangular emclosure, and a cube more so with congruent side, floor and roof dimensions.
We subdivide those square sides into three 1m x 3m panels, because many materials come in a meter-wide extrusions, and can therefore be integrated into our system, and because a door height requires a two-meter high opening.