Abstract: A process for forming a hollow, cured composite article. The process includes steps of making a plug from a meltable material. The plug is covered with a polymerizable material and the covered plug is inserted into a cavity formed in a thermally-expansive and heat-resistant polymer held within a rigid container. The almost filled container is covered and the container and part are heated to cause curing of the polymerizable covering. The cured assembly is removed from the thermally-expansive and heat-resistant polymer and heated to an extent sufficient to melt the core.