Nowadays, the challenge in nanolithography is the size, the shape, and the cost of the masks. In our laboratory, it has been possible to generate nanocrystals and to assemble them. Indeed, one of the interesting properties of these nanocrystals is their ability to form mesoscopic structures like lines and rings. We have used these two geometries as lithographic masks. Colloidal lithography based on 10 nm ferrite nanocrystals has been done. The nanocrystals are deposited on a silicon wafer covered with resist. Nanocrystals are arranged on the mesoscopic scale. Different patterns such as rings and straight lines made of nanocrystals are obtained. These patterns have been used as masks. The patterned substrate is then etched by reactive ion etching (O-2/SF6), and the structures (lines and rings) are transferred in the silicon substrate. This indicates that even very small nanocrystals are good candidates as lithographic masks; they can offer different geometries at low cost.