Using architectural shapes made from EPS (expanded polystyrene) for interior moldings is an incredibly easy installation and fix compared to other materials – yet looks exactly like those other options such as wood moldings. To achieve an effect that looks like ceiling beams, layers of lightweight EPS can be installed with a water-based adhesive. The beam is held in place with 2-sided tape while the adhesive dries; no nails or other complex attachment required. Once in place, the EPS beams can be spackled, sanded and painted to fit in with the rest of your interior décor scheme.