Introduction: Business Card Folding Sheet Metal Wrench

This documents the process of designing and building your own folding business card. A DIY business card engages the recipient to invest some time puzzling out the assembly, and learn how the designer's brain works. I encourage you to take the principles explained here and make your own unique design.

Step 1: Assembly

The piece was designed to assemble in 5 minutes or less.

I added twist locks so that you could use a dime, penny, or screwdriver to assemble. Parallel cuts were inserted where I wanted the metal to bend easily.

Step 2: You Will Need:

Laser Cutter:

  • Coherent Metabeam 400W laser cutter for metals
  • Epilog Laser for cardboard

Cardstock for prototyping: I used .024in thick chipboard, available on Amazon

Step 3: Initial Concept & X-Acto Prototyping

I used an x-acto knife and card stock to prototype my initial concept. I wanted complex curves on the wrench, so I did it the old fashioned way. The mortise & tenon joints and the soft curves with a different handle thickness proved very difficult to design in sheet metal tools, but easy to make out of paper.

I encourage you to explore design software such as Inventor Sheet Metal Tools to design your card, just be aware of the limitations of the software you are using, as it was primarily made to design housings and simple metal clips. When you're working with a high number of parts. and soft curves, it can get tricky.

Step 4: Design

At the time of building this, I couldn't find a software that I wanted to give me complex curvature I was looking for. I wanted it to have the subtle curves of a wrench with the tapered handle. So I drafted it the old fashioned way.

Theory: If you bend something, you can treat it as a beam. The top will stretch due to tension and the bottom will compress, but the absolute centerline, known as your neutral axis, will not. I used the exact middle of the thickness of the material as my neutral axis, and calculated the bend radii using a simple arc length formula.

Choosing .024'' thick chipboard, readily available from Amazon, I went to work. Everything was set parametrically, so that if you changed one variable, it would cascade down the design. Using this for slot width, with a .05'' tolerance to either side, the design changed.

The overall design uses a mortise & tenon design commonly used in woodworking. The tenon takes the form of tabs that fit into the slots.

The tenons have a notch that is specific to the thickness of a dime, so that someone can use a coin or screwdriver to twist and bend the legs in opposite directions, thereby locking the pieces into place.

Step 5: Prototyping & Iterative User Testing

Since the final version was to be made out of metal, I chose to cut the prototypes using Pier 9's Coherent Metabeam 400W laser cutter. The first version was prototyped out of plastic, as it was readily available at the workshop. It was fragile, and tended to fuse together where the laser cut it. I quickly moved to the chipboard, and started refining the design.

I would cut the initial prototype on the laser while refining the next iteration on the computer right next to it. If anyone walked by and asked about what I was cutting, i'd hand someone a card and watch them assemble it, and ask for feedback.

Using this iterative method allowed me to come up with several design features I hadn't initially thought of, such as staggered tabs and specific tenon widths to encourage the user to put the pieces in the right place. The layout was also modified to have the pieces closer to their respective sections.

Step 6: Design Finalization in Illustrator

Once the cut file was finalized, I took it into illustrator to get text and signature. With the input and assistance of my designer friend Scott Racette, I was able to make it beautiful, and add a signature.

Step 7: Cutting Metal With a Laser!

Now for the fun part:

Cutting metal on the Coherent Metabeam 400W laser cutter is a bit different than cutting pretty much anything else. It uses a capacitive touch sensor to give you the exact offset, and the metal sits on standoffs. You should make sure you're very comfortable with the Metabeam before going after a metal project.

In the Pier 9 workshop we keep an extra head just for this occasion, which stays clean and goes back in the case where it was found! This way we can keep cutting metal without all the nasties from wood, acrylic, etc affecting the quality of the edge.

Build notes: I changed the location of my tabs so that the wrench pieces would press out easily. The tabs sit in the middle of each longer piece, so you can use leverage to twist and shear them out without needing tools.

Some of detail was lost when importing it to Metabeam's software. The complex curvature of the signature confused the program, which required some manual toolpathing. The border of the piece didn't make it through, either, but i'm still happy with it!