A method of micro-machining comprising providing a primary region of at least a first material which contacts a second material at at least one end portion thereof, the method comprising providing an infill material on to the second material, patterning and etching said infill material to form a hole through the infill material to the second material, depositing the first material on to said infill material so that the at least one portion of the first material contacts the second material through the hole. The method can be used to provide a track bridging suspended portions of micro-machined structures. Also a method of narrowing and sealing top portions of channels cut into a wafer is disclosed.