The article describes procedures used by the Maxwell Museum of Anthropology to make accurate casts of masonry in Chaco Culture National Historical Park, New Mexico. Molds consisted of six to eight coats of acrylic rubber latex brushed on the stone walls and reinforced with two or three layers of glass fabric. Casts employed Shell Chemical 828 epoxy resin tinted to match masonry colors, a polyamide curing agent, Versamid 140, and fine glass fabric. Casting required use of a silicone or fluorocarbon mold release.