As part of a collaboration between Durham University and ESO, an experimental platform is presented whose purpose is for testing generic laser-based wavefront sensors (WFS) for adaptive optics. The Rayleigh Technical Demonstrator (RTD) has been designed to allow a laser launch and Rayleigh back-scatter collection by installing components solely on a Nasmyth platform of the William Herschel Telescope, La Palma. The aim is to provide a WFS testing port within the RTD, permitting new WFS concepts to be tested rapidly in conjunction. This means that the RTD only requires small modifications for each concept to be tested. The second goal is to permit near-contemporaneous comparison of WFS data with that from a tomographic WFS. Currently, the RTD is planned to trial with three "cone effect-free" WFS concepts as part of the CALDO project. Presented here is an overview of the RTD design with detailed information on novel components and design choices.