Kinetic Sheet Metal Lantern (Featuring Custom 3D Printed Bending Jigs)

As an Industrial Design student, I have always been captivated by the intricate light play of traditional Moroccan lanterns. Their complex geometric shapes, domed structures, and precise, hand-crafted perforations fill any space with a special kind of magic.

For this project, my goal was to create a contemporary interpretation of the traditional lantern. I wanted to take this timeless aesthetic and manufacture it using modern digital tools: 3D CAD modeling, laser cutting, and CNC press brake bending. The result is a steel lantern featuring a unique kinetic mechanism: when hung from its handle, gravity closes the lantern; when placed on a flat surface, it gracefully opens up. This Instructable will guide you step-by-step through the process—from designing the mechanism and geometry, overcoming manufacturing challenges with 3D printing, to assembling a dynamic, functional steel lantern.

Materials:

1. 0.8mm Steel Sheet: The core material for the lantern body.
2. 1mm Metal Wire: For crafting the carrying handle.
3. 3 Cotter Pins: Essential for connecting the kinetic moving parts.
4. Custom 3D Printed PLA Bending Jig: (STL file attached in the next steps).

Tools & Software:

1. SolidWorks (or any CAD software with Sheet Metal capabilities).
2. Sheet Metal Laser Cutter.
3. CNC Press Brake.
4. 3D Printer (for the jig).
5. Bench Vise.
6. Pliers.

The digital design phase was critical because this lantern is not a static object. Instead of a single closed body, I divided the lantern into three identical main shells that attach to a bottom plate. Each of these three parts features a dedicated sliding track (slot) that connects to a moving top plate using three cotter pins.

I worked within the SolidWorks Sheet Metal module, starting from a Base Flange and adding Edge Flanges. The biggest challenge was Design for Manufacturing (DFM). I had to design the geometry of the three parts in such a way that they could be bent on a press brake without the flanges colliding with each other or with the bending machine's tooling. This required careful planning of the physical bending sequence that we will execute in the following steps.

Once the design was complete, I exported the Flat Patterns to DXF files. I sent these files to the laser cutter to cut the 0.8mm steel sheet. You will need to cut: the 3 identical main shells, the bottom plate, and the top moving mechanism part.

For the kinetic mechanism to operate smoothly, bending the three main shells accurately is crucial. Because the parts have angled edges, it is difficult to align them squarely against the press brake's backgauges without slipping.

My solution was to design and 3D print a custom PLA jig that supports the sheet metal at the perfect angle.

Bending Sequence for the Main Shells:

Side Flanges: I placed the 3D printed jig on the press brake bed. The jig supported the steel sheet at a precise 60-degree angle. I used clamps to secure the part so it wouldn't shift during bending. I repeated this for all side flanges on the three identical parts.

The Top Area: For the section that connects to the center, I started with an initial 50-degree bend on the press brake. At this point, the geometry became too closed, risking a collision with the machine. I transferred the part to a bench vise and carefully finished the bend manually to a precise 60 degrees.

Bottom Tabs: Finally, I bent the small tabs at the bottom of each part to 60 degrees. These will be used to attach the shells to the base.[Insert photos here: The metal on the blue jig in the press brake (image_4.png), and the vise bending

The final part that requires bending is the heart of the kinetic mechanism—the top piece that moves up and down, causing the lantern to open and close. Bending this part requires a series of precise actions in opposing directions:

1. Bend the three tabs of the part upwards to an angle of 65 degrees.
2. Perform a secondary bend on these tabs in the opposite direction to an angle of 55 degrees.
3. Finally, bend the specific tabs containing the holes (where the cotter pins will go) in the opposite direction to the first bend, to an angle of 95 degrees.

Now that all parts are cut and bent, it's time to bring everything together!

1. Attaching to the Base: Insert the bottom tabs of the three identical main shells (the ones bent to 60 degrees) into the designated slots on the bottom plate to secure the structure.
2. Assembling the Mechanism: Place the moving mechanism part at the top center of the assembly. Thread the 3 cotter pins through the long sliding slots of the three main shells, and into the holes of the moving part's tabs. Bend the legs of the cotter pins outward to lock them in place. The top part can now slide freely up and down the tracks!
3. The Handle: Thread the 1mm metal wire through the designated top holes. Use pliers to bend and shape the wire into a functional carrying handle.