The use of embedded PC in control systems is increasing. There exist a significant number of real-time operating systems but RT-Linux provides several advantages over most of them. RT-Linux shares the processor with standard Linux allowing to run accurately timed applications to perform data acquisition and control systems with Linux applications. However, the possibility of tailoring the Linux to build small versions with specific services permits to build embedded systems. The development of drivers to handle specific control devices and the availabity of high level services at the Linux level make the advantages overcome the drawbacks of use Linux for many control applications. Anyway, customising Linux for this kind of small hardware is not a straightforward work. In this paper we describe a tool RT-LEAST (Real Time Linux Embedded Autonomous System Tailoring Tool) to automatically tailoring and installing a great variety of embedded systems minimising their requirements. Also, RT-LEAST is applied to design and develop a control application showing the benefits of the process development and the low hardware requirements obtained.