Everything You Always Wanted to Know About Cardboard

Daily tous les jours was invited by Autodesk to take part in SF’s Market Street Prototyping Festival 2015 edition, a 3 days event geared towards imagining the future of..well Market Street.

Read more about the project here.

The festival being focused on rapid prototyping, we were offered by Autodesk to use their Pier9 machines wonderland for all our fabrication needs. The modern maker’s equivalent to Willy Wonka’s factory.

We decided to work with cardboard as a key design element, and we’ll try to share here what we learned along the way. Hopefully what we learned can be applied to any other big-scale cardboard project you might want to make.

Please bear in mind that even if cardboard was selected for its aesthetic and its kindness to Mother Nature, a metal structure is actually holding everything together and making it sturdy.

The project is made of 4 traffic lights, 2 on each side of the street.

We first started experimenting with cardboard using basic boxes from Home Depot, hand cut and stitched together to create a first full-scale prototype that we took out to the winter streets of Montreal.

Each pole is made of:
2 boxes (in which will sit the lights, a speaker and some cables) 1 triangular pole

Cardboard allowed us to have a good visual impact. Even though the poles would have to compete with tall buildings and other giant-scaled urban elements, they would still be visible from afar.

Even from the other side of the street when buses and streetcars are trying to hide them, as shown on the very preliminary non-computer-assisted simulation above.

Even more important, cardboard meant that a big part of the project was recyclable after the 3 days of the festival.

There is a couple types of cardboard out there, the most common being corrugated cardboard.

The strength of a cardboard piece is essentially defined by its number of “plies”. A ply is made of an accordion-folded paper or thin cardboard sheet (called “flute”, see next step) glued between two thicker sheets of cardboard.

Where your general moving box is only made of one ply, both Wikipedia and reality checks seem to agree on the fact that multi-ply cardboard has a higher creasing and folding performance. As final look and robustness were for us important criterias, it seemed we just found a new best friend in the person of multi-ply cardboard.

A piece of cardboard is also identified by its type of flute, which is:

the number of “waves” or flutes over a given linear foot or meter the thickness of these flutes (these may vary slightly from one manufacturer to another)

*the most common type of flute in corrugated cardboard

When it comes to creating joints to connect several pieces of cardboard, you have a couple options.

Here are some references we stumbled upon during our research:

• You can cut slots and slide them into each other,
• fold it on itself, like this or that,
• stack several pieces together to create a very robust piece,
• or even use one of these Makedo construction kit.

Another very useful reference, is Jude Pullen’s website about modem making. It is a wonderful place to start.

In our case, the traffic lights’ boxes have a rather traditional shape so we ended up using ready made boxes (see next step on Sourcing the boxes). These boxes being only one piece, they are pretty robust and even more once they are closed.

The long poles are a bit different. They are triangular, 10 ft. high, and we need to be able to access the tech sitting inside them. They also are one single piece of cardboard, except this one is wrapped around the metal pole and closed on the back by screwing together two overlapping flaps using bolts, nuts and washers.

Pro tip: If you want to avoid wrinkles along your fold, you should insist on scoring beforehand.

Having a better understanding of what type of cardboard we were looking for, we started searching for a supplier crazy enough to sell these over-dimensioned pieces.
It turned out that Custom Made Boxes is one of these. As you’d expect from their name, they sell custom-sized boxes, even in small quantities. The boxes can even be delivered pre-scored, which is very helpful when trying to fold cleanly a two-plies sheet!

Once you’ve placed your order, wait a few days and receive your delivery!

From all the tools available at Pier9, the one that would fit best our needs regarding cardboard was the Metabeam 400W laser cutter. With its bed side of 4’ x 4’, it can almost perfectly accommodate our boxes.

Yes, “almost”. Because of their closing flaps, the boxes turns out to be slightly too tall.

If you want them to fit in the machine, you might want to gently fold these flaps and keep them weighted down during the whole cutting procedure.

As you can see and would expect, each box is delivered flat. But because we needed a different cut on each of the 4 sides, we had to find a way for the laser to cut ONLY through the top layer and not both at the same time.
You can use for instance a thicker material (like ⅜” plywood) to slide in between your 2 layers of cardboard. It will do the job just fine but depending on your designs your cut might not be as clean as the laser gets closer to the edges, because the top layer will bend slightly.

By experimenting with the Metabeam’s settings, we managed to find a power / speed combo that would make it to cut only through the top layer.

In order to suspend precisely and robustly these boxes at ~10 ft. high from the ground, we had to find a solution to anchor them at the structural metal pole. We designed a piece made out of 1” thick plywood (codenamed “sandwich”), which was slid inside the boxes, aligned with the holes drilled into the metal pole, then attached using ¼” screws.

That solution had also allowed us to mount the tech living inside (speakers and DMX controllers).

These pieces have also been cut on Pier 9’s Metabeam. The glue used inside the plywood produced some interesting flames...but by adjusting both power and speed, we were able to cut through the material without any dramatical consequences. Just a lot of smoke.

If there is one thing we learned from the past years spent working in the public realm: never underestimate Mother Nature! She always finds a way to make your life a bit less easier.
By working with cardboard, in a city with such an unpredictable climate, we knew we were flirting with trouble.

This is why we wanted to take all necessary precautions to waterproof the cardboard components of the projects. There are many products out there to do that, but most of them make the cardboard unsuitable for recycling. After a detailed research and some tests, we decided to use a natural wax (Trewax paste wax). This product gives cardboard water-repelling properties, AND leaves it suitable for recycling. It also has the big advantage of preserving the visual aspect of the cardboard, where other products tend to alter its natural tint.

Once the waxing process is done, the boxes are ready to be assembled.
In our case, it meant mounting them by pairs (using the “sandwich” piece mentioned previously), mounting the lights and other decorative elements.

After that, the cardboard pieces were taken to Market St., where final tech assembly and installation happened.
And voilà!

Cardboard is an interesting material to work with. It is cheap, easy to transform, and recyclable. It was definitely challenging to work with it at that scale, but what we learned along the way was worth taking the risk.