As has been demonstrated in the “microfactory” which is a miniature manufacturing system proposed by the author’s research group, small machine tools that are comparable in size to their target products lead to large reductions in energy consumption and area. Experiments showed that they were capable of micro mechanical fabrication. However, the design of miniature machine tools has not been fully optimized. The author proposed a design method to estimate machine tool performance. In this paper, the design tool is applied to find miniaturizing strategies. By applying the design tool, it is possible to determine which of the design parameters and error sources would significantly affect machine performance. From the results of calculation, the tool can clarify the effect of machine tool sizes imposed on the machine performances. This leads to some suggestions regarding machine tool sizes. Finally, design guidelines for miniature machine can be obtained.