EMT (Electrical Metallic Tubing) conduit is affordable, reasonably sturdy and readily available. A company called Maker Pipe makes it easy for you to build stuff using EMT. Their eponymous product is a series of steel connectors for joining the pipes. In addition to 45-, 90- and 180-degree connectors, they offer T-connectors, an adjustable-angle version, 4-way connectors and even 5-way connectors. They come in different size and can cover ", " and 1" conduit.You only need a single tool to work with these: A 5mm hex wrench. (Well, and a pipecutter.)The connectors run roughly $3 to $6 a pop, with lower prices available in bundles.