To facilitate the attachment of mounting plates to the sides of a truss or frame structure, the Horizontal Tube Flange connectors can be utilized. To use properly, the semi-circular portion is bonded to a carbon fiber tube, and the mounting plate is bonded to the flat side. Using multiple horizontal tube flange connectors spaced out across the truss tubes provides an ideal means to bond on mounting plates. Care must be taken to ensure proper loading of the plates so that the adhesive is never subjected to high peel stresses, which could cause the bond to fail. These connectors are suited for lightweight mounting plates and fixtures with flat mounting surfaces. Examples include robotic end effectors, electronic rack shelving, support plates for scientific equipment, and table tops.