The Japanese art of origami (‘ori’, fold; ‘kami’, paper) has long enabled the creation of beautiful three-dimensional sculptures from flat sheets of paper. More recently, origami has also found use in various engineering applications, leading to the development of origami-inspired systems ranging from the macro to the micro scale. At and below the micron scale, origami-inspired design has proven to be especially advantageous by allowing the use of planar microfabrication methods to build systems that can self-fold into complex three dimensional geometries. In this thesis, we explore ultra-thin sheets of hard materials as a platform for origami-inspired microsystems. We use atomic layer deposition (ALD) technology to grow inorganic films with nanoscale thickness, and integrate these films into complex microfabrication processes to create releasable micromechanical devices that can self-fold. The approach we develop combines planar semiconductor fabrication methods with computerized origami design, making it possible to fabricate and deploy origami-inspired microdevices en masse. Due to its generality and applicability to various classes of materials, our approach presents as an ideal platform for the miniaturization of origami-inspired machines and robotics.