We propose a generic, simple, and parallel nanofabrication technique to obtain three-dimensional multiscale nanostructures based on stress-induced cracking of thin film polymeric microstructures at their sharp edges. The technique was applied to obtain an array of nanochannels on large areas (-squared centimeters) with channel widths and heights of similar to 100 nm. The technique offers flexibility in nanofabrication by providing very simple controls on the feature size, aspect ratio, and the complexity of the nanostructures thus obtained.