Force microscopy has been used to machine nanocrystals of MoO3 and manipulate the resulting objects into new nanostructures. MoO3nanocrytals were grown on the surface of MoS2 by controlled thermal oxidation. These nanocrystals may be moved and modified with a force microscope by controlling the applied load. The crystallite/substrate interface is shown to constrain the motion of the crystallites to the lattice rows of the substrate, a phenomenon we term lattice-directed sliding. The strength of this effect is such that attempts to move crystallites off axis result in their being machined, and thus it is possible to selectively move and modify these nanocrystals. The lattice directed sliding phenomena has been used to determine for the first time the friction between two atomically aligned and flat surfaces, thus providing new molecular level insight into friction. Significantly, we have expoloited these observations to fabricate interlocking nanostructures that can be reversibly connected.