A joint coupling for axially connecting together a first joint and a second joint, which includes first and second joints each having a complementary member sized and shaped so that, when the joints are properly aligned, the complementary members form an overlap structure which is effectively a continuation of the first joint or the second joint, and a sleeve which is slidable over the overlap structure to secure the joint coupling. The inside surfaces of the sleeve are tapered, as are the outside surfaces of the overlap structure such that when the sleeve is slid completely over the overlap structure, the inside surfaces of the sleeve make full contact with the outside surfaces of the overlap structure to firmly secure the joint coupling. Two or more joints may be joined at any desired relative orientation by use of a hub which has complementary elements which can accommodate the complementary members of the joints. The joint couplings can be readily used to create complicated structures of virtually any desired shape.