A spin caster for spraying a surfacing material upon an interior surface of a vessel includes a spin head configured to rotate about an axis, the spin head including an input port, and a supply line coupled to the input port and configured to convey a first material to the spin head and a second material to the spin head. The supply line comprises a first channel configured to convey the first material to the spin head and a second, different channel configured to convey the second material to the spin head.