How do a paint a smooth finish in my house?

Construction of the Xanadu house in Kissimmee, Florida, began with the pouring of a concrete slab base and the erection of a tension ring 40 feet in diameter to anchor the domed roof of what would become the "Great Room" of the house. A pre-shaped vinyl balloon was formed and attached to the ring, and then inflated by air pressure from large fans. Once the form was fully inflated, its interior surface was sprayed with quick-hardening polyurethane plastic foam. Spraying from the inside permitted work to continue even in wet or windy weather. The foam, produced by the sudden mixture of two chemicals that expand on contact to 30 times their original volume, hardened almost instantly. Repeated spraying produced a five-to-six-inch-thick structurally sound shell within a few hours. Once the foam cured, the plastic balloon form was removed to be used again. Once the second dome was completed and the balloon form removed, the two rooms were joined together by wire mesh which was also sprayed with foam to form a connecting gallery or hall. This process was repeated until the house was complete. Window, skylight, and door openings were cut and the frames foamed into place. Finally, the interior of the entire structure was sprayed with a 3/4 inch coating of fireproof material that also provided a smooth, easy-to-clean finish for walls and ceilings. The exterior was given a coat of white elastomeric paint as the final touch.