Plan custom workbenches, desk frames, shelves, and equipment stands in a desktop browser. BeamJoin combines an AI design assistant with an editable 3D workspace for aluminum extrusion structures. Describe a requirement in natural language, revise extrusion dimensions and positions, add panels, connectors, and holes, then export material and machining information as PDF or Excel files for supplier discussions. This is an exploration of AI in traditional industrial design workflows. Manual design and existing exports are free; platform AI usage consumes credits. Chinese and English are supported. Load capacity and manufacturing suitability require verification for the actual materials and assembly.