Three-dimensional (3D) imaging through a compact device could enable many applications in mobile consumer electronics and biomedical endoscopy. Conventional 3D cameras are bulky and require taking multiple photos to synthesize a 3D scene. Here, I will introduce a new type of 3D camera. It replaces all the bulk optics by a single layer of optical mask and can be made very compact. It takes a snap-shot of the 3D object or scene, and then recovers the 3D information through computational algorithms. Here, I will discuss the two 3D cameras that we recently developed, which can image 3D microscopic objects or 3D macroscopic scenes. Both cameras are composed of a single piece of randomly positioned microlens array and an image sensor. We develop highly-efficient computational algorithms to reconstruct the 3D objects and 3D scenes from a single camera exposure. Our 3D cameras open new avenues for high speed 3D imaging with a compact device footprint. For more information, please contact the ES Department at (707) 664-2030 or engineering@sonoma.edu