Abstract: An improved method for making leak-proof connections to fuel tanks and other hollow articles rotationally molded from synthetic resinous materials, and particularly from relatively soft materials such as polyethylene. Prior to molding the article in a conventional rotational mold process, one or more male or female studs or similar threaded fittings are bolted to or otherwise temporarily held against the interior surface of the mold at a location which corresponds to the location for the leak-proof connections in the finished article. When a number of threaded fittings are located relatively close together or are spaced around an opening in an article, the fittings are preferably interconnected by wires or other metal support members which is embedded in the finished article. The support member strengthens the connection and also maintains a fixed spacing between the fittings. The article is then rotationally molded such that the fitting is embedded in the wall of the finished article.