Fabrication of three dimensional micro structures in silicon and silicon related materials is becoming increasingly important for the realisation of micro systems comprising of sensors, actuators, transducers and analytical assemblies. Fabrication of such devices so far has been mostly in form of structures defined by the crystal planes of silicon, or has involved sophisticated technologies such as ion beam machining, replication using LIGA, or micromachining techniques involving a sequence of alignment and etch stages using binary masks. Structures with circular symmetry are of great interest as micro optical components amongst others, and these are not easily amenable to microfabrication techniques commonly employed.