We shall demonstrate the use of neutron reflectometry to obtain three-dimensional structures in a non-invasive experiment. Spinodal dewetting is one of the few areas where peristalsis (the mechanism by which the digestive tract moves food) occurs in the physical science. Here, a film spontaneously ruptures due to long-range forces, which act across the film. We propose to study a three-layered structure of poly(methyl methacrylate) sandwiched between two polystyrene layers, with the polymers chosen to have matched viscosities, which makes the effect much more visible. Spinodal dewetting causes the capillary waves at the interfaces between the polymer layers to be amplified, which leads to rupture. The increase in these capillary waves can be detected by the off-specular reflection of neutrons. It is this new technology that we shall harness in order to demonstrate the effect.