Maskless patterning of materials using focused ion beams are important to simplify device processing and to develope full maskless processing. We have shown that a high speed maskless patterning can be done using ion beam assisted etching and ion beam modification techniques. In this paper, basic characteristics of various liquid metal alloy ion sources and a mass separatted focused ion beam system, and maskless patterning techniques for GaAs, Cr films and other materials are reported.