Made of silicon rich nitride, this initially flat structure was folded into a pyramid using the surface tension of water. The final shape is programmed by complex hinges machined to stop folding at the desired angle thanks to corner lithography. A great variety of 3D structures can be self-folded simply with droplets of water.
Legrain, A.B.H. (2014) Elastocapillary self-folding of micro-machined structures. PhD thesis, University of Twente. ISBN 978-90-365-3759-9