Multi-touch interaction with computationally enhanced surfaces has received considerable attention in recent years. Hardware implementations of multitouch 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 practicalities 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.