Abstract: Multi-touch interaction with computationally enhanced surfaces has received considerable attention in recent years. Hardware implementations of multi-touch interaction such as frustrated total internal reflection (FTIR) and diffused illumination (DI) have allowed for the low-cost development of surfaces. Although many of these technologies and associated applications have been presented in academic settings, the practicality of building a high-quality multi-touch-enabled surface, both in terms of the software and hardware required, are not widely known. We draw upon our extensive experience as developers of multi-touch technology to provide practical advice in relation to building and deploying applications upon multi-touch surfaces. This includes technical details of the construction of optical multi-touch surfaces, including infrared illumination, silicone compliant surfaces, projection screens, cameras, filters, and projectors, and an overview of existing software libraries for tracking.