Cardboard prototyping

Ordering acrylic or steel plates from online services can be quite expensive depending on your location. I didn’t want to waste money before I’m confident with my physical layout, so I used cardboard to test multiple designs.

While an acrylic or steel plate may look sturdier and more professional, cardboard is excellent for quick prototyping and more practical compared to e.g. acrylic in many ways.

Prototyping with cardboard described below has its drawbacks too. You may have waste amounts of cardboard at home for free, but this method will cost you a lot of time. It’s OK for a weekend build, but after I went through this a few times, I will probably ask somebody to lasercut the cardboard for me next time.

That being said, this is how I’ve done the cardboard prototype of the Tormentor:

Material

There are all kinds and thicknesses of cardboard. I’ve found shoeboxes are the best for such projects. Get a shoebox. It doesn’t have to look fancy, the switches and keycaps will cover it anyway.

For this build I had this at hand:

Tools

These were the tools I’ve used, but you should be able to do this with an exacto knife and some pins only. If you don't have a cutting board replace it with another cardboard. Instead a steel ruler you can use a plastic card.

Process

I liked the mountains on the top of the box.

If you can print on cardboard that will make the job easier. I’ve printed my layout on a sheet of paper instead and had to transfer the cutouts, screw holes and contour somehow on the cardboard.

Secure the drawing with some pins to prevent drifting. I’ve used the screw holes to pierce some dressmaking pins through into the cardboard.

Mark the screw holes and corners of cutouts on the cardboard by piercing through the printed layout.

For a good fit of the switches I aimed for the inner side of the squares.

Once finished, you get something like this.

Now, time to grab the ruler and exacto knife.

If the array of dots confuse you, you can draw some lines with a pencil to ensure you know what you should keep and what area is waste.

One direction at a time proved to be more efficient.

The process is quite slow, but if you are not going to publish pictures about it, you don't have to be that precise. You have to cut multiple times to cut through the cardboard, especially if you are cutting against the grain.

Doing the other direction means you are more than halfway through.

An hour (!) later I’m done with the cuts. Without taking pictures and aiming for nice cuts it could have been done much quicker.

Remove the waste material.

Fit your switches in the cutouts. It’s a nice, firm fit, they grab in the side of the cutouts and don’t fall out (unlike from an acrylic plate). Quite the contrary: you have to be careful if you want to remove a switch to not to tear out a piece from the cardboard.

Screwing in the plastic stand-offs. They are cheap and look nice IMO. I’ve ordered an assortment of M2 stand-offs and screws with different lengths to test what lenght I need. 5-6 mm is OK for my handwiring with hot-swap sockets, I'll purchase only those ones next time.

I really like how these little black screws look. Their size is perfect too.

I’ve cut the contour of the plate. There were some areas where I would ruin the plate if I'd stuck to the original path. It should work with laser cutting, but not with scissors. I didn’t want to force anything.

To ensure the cardboard won’t flex, I used more stand-offs than I would with an acrylic or steel plate.

And the finished mock-up ready for some abuse, without wiring yet. In this stage you can already test how natural the typing feels on your layout.

I planned this version to be temporary, but with the proper amount of standoffs the cardboard prototype turned out to be sturdy enough for me to use for nine months before I felt I should try acrylic and later stainless steel plates.

Thanks for reading. For wiring check the build log of the S.Torm46.