I have been involved in yacht design for the last 8 years and thus have developed high interest related to technical difficulties and solutions in compacting, optimizing space and systems on yachts as to reduce cost and maximize living area.
I have recently decided to apply these to constructions on land since it is obvious to me that we have to optimize our living areas as to make them more efficient in many ways.
a few examples
Translucent Cement http://www.litracon.hu/aboutus.php
Or this toilet which flips down and saves space
Or this toilet and sink combination W+W by Roca which saves space and water