The Standard Model of particle physics, although successful, is known to be defcient both theoretically and experimentally. Many proposed extensions to the SM predict the existence of Weakly Interacting Slim Particles (WISPs). In this thesis the construction and results of the CASCADE microwave cavity light shining through a wall experiment will be presented. In addition to CASCADE, this thesis will present a novel realisation of a light shining through a wall experiment using photonic bandgap structures to probe otherwise unreachable regions of the WISP parameter space