a process for preparing a composite hollow body article by means of injection molding is disclosed . the process includes the steps of : providing a hollow body having exterior surfaces and interior surfaces , the interior surfaces of the hollow body defining a hollow interior , the hollow body also having at least one opening which provides fluid communication with the hollow interior thereof , introducing a substantially incompressible fluid into the hollow interior of the hollow body , the hollow interior being substantially filled with the substantially incompressible fluid ; and injection molding thermoplastic material onto at least a portion of the exterior surfaces of the hollow body .