While freestanding bottles tend to break easily, truss structures essentially consist of triangles. In such an arrangement, it is the structure that prevents de-formation, not the individual bottle. The main strength of trusses is that they turn lateral forces (aka bending moments) into tension and compression forces along the length of the edges (aka members). Bottles make great members: while they buckle easily when pushed from the side, they are very strong when pushed or pulled along their main axis. TrussFab affords building trusses by combining tetrahedra and octahedra into so-called tetrahedral honeycomb structures.

Step 2: Editing. We implemented TrussFab’s editor as an extension to the 3D modeling software SketchUp. TrussFab’s editor offers all the functionalities of the original SketchUp system, plus custom functions that help users create sturdy structures. In particular, TrussFab’s editor offers primitives that are elementary trusses (tetrahedra and octahedra), tools that create large beams in the form of trusses, and tools for tweaking the shape of structures, while maintaining their truss structure. TrussFab’s integrated structural analysis calculates the internal forces in the structure and warns users if it would brake.

Step 3: Hub generation. After designing a structure, TrussFab’s hub generator generates the 3D models of all hubs. The system genarates 3D printable hubs for spacial structures and laser-cuttable 2D hubs for facades, as shown in the figure below.

Step 4: Fabrication. Users then send the 3D model files produced by the hub generator to one or more 3D printers in order to manufacture them.

Step 5: Assembly. Users finally manually assemble their structures by following the unique IDs embossed into each hub.

We have validated our system by designing and fabricating tables and chairs, a 2.5 m bridge strong enough to carry a human, a 5 m high pavilion consisting of 1280 bottles and 191 3D printed hubs, presented at CHI'17 in Denver.