Schluter’s Kerdi-Shower-ST prefabricated shower base is part of the company’s series of new shower components that are designed to speed the process of waterproofing a shower prior to tile installation. The sloped base is made from expanded polystyrene foam that can be cut with a utility knife and installed with thinset. It’s available in six sizes, from 38 by 38 inches to 72 by 72 inches, with prices from $65 to $200. Each base has a drain hole sized to accept the company’s shower-drain product.