I just stumbled upon:
http://dspace.mit.edu/handle/1721.1/37400
Providing adequate energy to developing countries is one of the greatest global technical challenges today. Fabrication is undergoing a revolution that parallels the digitization of computation and communications. Emerging affordable, "desktop" fabrication tools are providing the precision and repeatability necessary for regular people to design, manufacture, and install a system to convert solar thermal energy to useful work. In the spectrum of devices that use solar energy, this field-fabricated system exists in a space between crude solar cookers for heating food and complex, expensive photovoltaic cells. Computer control and high precision allows regular people to experimentally converge on a locally-appropriate design and implementation to solve the challenge of providing energy. This thesis describes a field producible, small-scale turbine that uses solar thermal energy to provide mechanical energy. I investigate a solar thermal steam-driven turbine system and build and evaluate several versions in field fabrication lab locations around the world. I consider the efficacy of deployment in rural developing areas.
He explicitly mentions 3D printing as the best way to produce the boundary layer turbine.
What do you think? would this be feasible with RepRap?