Predictably, I thought to myself: “I can make that”. This kind of thought is a blessing and a burden, and a recurring theme for me.

A few years ago, after my wallet started to fall apart, I became interested in leather-working. I couldn’t find a new wallet that I liked, and the slimline card wallets I found were too expensive, being only two bits of leather sewn together.

Predictably, I thought to myself: “I can make that”. This kind of thought is a blessing and a burden, and a recurring theme for me. It feels good to make things, but it can eat up my time. Often much more time than I thought it would at the outset. More on the Human Planning Fallacy another day.

Over the years I’ve made a leather key fob, leather travel cord organiser, and a sheath for a blade (an old handheld scythe that I use to cut the grass – but that’s another story). I did make that wallet, too.

But my pieces were looking a bit plain, and I started looking into adding some flourishes, by stamping and embossing the leather with patterns. Here is how I’ve been able to create my own leather stamp with a 3D printer.

Shortcut: You can download the file for your 3D printer below! Just enter your email and we’ll send it to you.

Process

It’s OK, “engineering is an iterative process”.

I designed the stamp on my computer, turning an image file into a 3D printable file, then printed it. More details on each stage below. Overall, the time for each stage was:

2 hours – Design

1 hour – 3D printing

24 hours – Stamping

I also faced a number of challenges that taught me some valuable lessons along the way. Often, they sent me back to the drawing board. It’s OK, “engineering is an iterative process”. These included:

Licencing of images,

User interface quirks of software,

Mirroring the image, and

Printing small items

Keep an eye out for these below.

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Making the stamp

Better to stick to my own intellectual property in this case.

The stamp that I made was 3D printed on an Ultimaker Original, but it took a lot to get to this point. The steps are:

Convert an image file to vector format – with Inkscape

Use the vector file to generate a 3D shape – with 123D Design

Print the stamp – with Cura and an Ultimaker Original

Convert an image file to vector format – with Inkscape

Start with a .png or other image file that you want to turn into a leather stamp. Import the image into Inkscape, which is a free vector editing program. You can use Inkscape to clean up the file and turn it into an .svg file, which is needed for the next step.

Lesson #1: At first, I wanted to create a stamp of an interesting map that I had found, called a Dymaxion Map, or Fuller Projection Map. This map is interesting for a number of reasons, most of all because of it’s low distortion of the land masses. But this map is trademarked by the Buckminster Fuller Institute, and is only available for use through a licencing agreement. Better to stick to my own intellectual property in this case. You can read about the Dymaxion Map over at bfi.org.

A vector file differs from a normal image (or raster) file in the way it stores the shape and colour information of the image. A raster image is a series of pixels, each with their own colour and location. The image looks fine if you are using a normal resolution, but as soon as you try to zoom in the output becomes very blocky.

By contrast, a vector image stores the shape data in the form of a line equation. This way, no matter how far you zoom in, the image will always have smooth edges. This is also a prerequisite for using the image for 3D printing.

Original .png raster image file

Use the ‘Trace Bitmap’ function to convert the raster .png image into a vector format. This algorithm processes the image and makes an approximation of the image in a vector format. You can control how accurate it will be – more accuracy simply results a larger output file.

For us, lower quality is fine, as the final stamp’s resolution will be limited by the 3D printer. I even went so far as to use the ‘Simplify’ function to reduce the complexity of the vector file some more.

Lesson #2: Remember to click on the image in Inkscape to select it, before using the ‘Trace Bitmap’ function. Missing this caused me a fair amount of confusion!

Inkscape .svg vector image file

Comparison between raster image (left) and vector image (right)

Next, adjust the dimensions of the .svg image to match your intended stamp size. Doing this at a later stage will reduce the quality of the stamp.

Lastly, save the file as an .svg file, ready for the next step.

Using the vector file to generate a 3D shape – with 123D Design

Next, start up 123D Design – a free Autodesk CAD program. Here you can import an .svg file as a sketch.

.svg file imported into 123D Design as a sketch

Firstly, double-check the sketch is the size of your intended stamp. If not, go back and change it in Inkscape, and update the .svg file.

Next, simply extrude the sketch until it is about 4mm thick, which should be plenty for a leather stamp. I also built a backing board around all the pieces for structural strength, and to keep all the little stamp pieces in the right place, about 2.5mm thick.

Lesson #3: When I printed this out the first time and stamped my piece of leather, the image was mirrored on the leather! For the final product I made sure to mirror the shape before printing, so the image was stamped the correct way around.

Extruded shape in 123 Design

Text with support base added

Mirrored

Lastly, export the file as an .stl file ready for printing.

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Create a printable file – with Cura

Cura is the software that comes with an Ultimaker, but any 3D printing software will do the job here. Import the .stl file, and we are ready for the following adjustments.

I used PLA with a 0.1mm layer height and 0.4mm nozzle. My wall thickness was 0.8mm with an infill density of 20%. These are standard printing settings for an Ultimaker of this style.

The only special function that I used was ‘Enable Ironing’, which attempts to smooth out the top layer. This helps remove the printing lines from the finished leather piece.

Lesson #4: Also after the first print. I found that the outline of the text “Engineering” was too thin to be printed. As a result, I went back to 123D Design and filled in the inside of the text with a further extrusion.

Print setup in Cura, with the old text outline

Printing on a (bright red) Ultimaker Original

The finished print, with the filled in text, before manual clean-up

The print took about 45 minutes.

Feel free to download a copy of the .stl here. Just enter your email and we’ll send it to you!

Applying the Stamp

The leather I used is approximately 3mm thick and dark brown. I purchased it for about AUD$25 at the The Fabric Store in Sydney. It was about a square meter to start with. I only used a piece about two inches long for this stamp.

To stamp the leather, you’ll need a few things:

Leather and stamp

Two pieces of timber

Two clamps

First of all, soak the leather in water until it is wet through. This helps it to form around the stamp.

Place the stamp face down on the smooth side of the leather, and sandwich this between the two pieces of timber. The timber spreads out the force of the clamps for an even pressure on the stamp.

Lastly, use the two clamps to squeeze it all together, increasing the pressure on each clamp incrementally and alternately to keep the pressure even. Don’t put too much pressure or the stamp will crack – it’s only plastic after all. The stamp should sink into the leather a bit.

You may need more timber and more clamps for larger stamps.

Clamping

Wait

I left the stamp in the clamps for 24 hours to be sure. You can experiment with shorter times, but I found that only an hour or two is not enough for the imprint to take hold.

Some of us are more impatient than others (this was eating into her dinner time)

Outcome

The finished product

The stamp could probably do with a bit more cleanup with a small abrasive tool remove any leftover printing debris, but I was pretty happy with the outcome.

I’m already pondering the next design – “I can make that”.

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