A simple stand-alone scanning tunnelling microscope (STM) has been designed and constructed. It employs a spring-diaphragm assembly for a coarse approach and a concentric tube assembly as the scanner. It is functionally capable of STM operation (constant current, constant height, line test) and STS operation (I-V and d/dl/V-V). The interfacing hardware/software design makes maximum use of standard commercial components/packages. The outline design procedure and results are presented.