The eTrament project



There are two men inside an artist, the poet and the craftsman. One is born a poet. One becomes a craftsman.”

—Émile Zola

There are two men inside an artist, the poet and the craftsman. One is born a poet. One becomes a craftsman.”

—Émile Zola

In the preceding articles we wanted to concentrate on the aspects related to the conception and design of the eT-pen, leaving aside the actual manufacturing activities. In this last issue of the Blog, we want to focus on the step-by-step production process.

3D Printing: From CAD models to tangible objects

Manufacturing the eT-pen starts by 3D-printing a CAD (computer-aided design) model of the stylus and its components. If you want to learn more about the CAD modeling of our pen, we invite you to read our previous article “Purposefully Designed”. We use a 3D-printing technology called stereolithography (SLA), which is an additive manufacturing process that belongs to the family of vat photopolymerization. In SLA, an object is created by selectively curing a photosensitive polymer resin layer-by-layer using an ultraviolet (UV) laser beam.

Here is how the SLA fabrication process works: First, the build platform is immersed in a bath of liquid resin at a distance of one layer height from the bottom of the tank. Then a UV laser creates a layer by selectively solidifying the resin. The laser scans the whole cross-sectional area of the model with the help of a set of mirrors, called galvos. The tank has a transparent bottom that allows the light of the laser to pass through but prevents the resin from spilling out.  When the layer is finished, the cured resin is detached from the bottom of the tank, in a process called the peeling step. Then the platform positions again at a distance of one layer from the bottom of the tank and the process repeats. The object is built facing upside down.

Before loading our model into the printer, we need first to set up the print’s layout, the orientation of the part in the build volume, and then add the supports. The forces applied to the print object during the peeling step may cause it to detach from the build platform. These forces are determined by the orientation of the object in the build volume. For this reason, the orientation of the object is a crucial step.

SLA uses scaffoldings to support the parts that dash in the vacuum. The principle is the same as that applied in the construction of buildings to prevent overhangs from falling. Support structures are printed in the same material as the object and must be manually removed after printing. The orientation of the part determines the location and amount of supports.

Finally, the model needs to be cut into thin layers with the help a slicer software. Each slice corresponds to a layer during the printing process. The instructions are then sent to the 3D printer.

3D printing a part can take from few hours to various days. There are several factors that dictate how long it takes to print an object. These include the overall size and the geometry. The part’s footprint, or the area it occupies on the build platform, is an important factor. The larger the footprint, the more area needs to scan the laser to complete each layer, and the more time the printer will take to print one single layer. While footprint is important, the build height of a part is probably the single most important dimension in determining how long it will take to 3D print. A part like the barrel of our pen, which is about 160mm height, is sliced into 3200 layers of 50 microns each. Printing each layer takes on average 30 seconds, which means that printing one single barrel takes about 27 hours.

Cleaning raw prints

After printing, parts do not come out of the printer fully finished: they require further post processing.

Since the printed objects are continuously immersed in a liquid resin bath during printing, they come out of the printer covered with uncured resin. We then need to rinse them off. The washing process is performed in two steps. Printed parts are first cleansed using an automated washing machine that cleans parts by soaking and stirring them into agitated highly concentrated isopropyl alcohol. Because printed parts have cavities (as is the case with the cap and the barrel of our pen), then a further manual cleaning is required to get every nook and cranny perfectly clean.

When an SLA part finishes printing, the polymerization reaction is not yet completed. Parts are in a “green”, no-fully-cured state and require further polymerization under UV light. For that, we employ a curing chamber that combines temperature and UV light allowing for finely tuned curing times.

The next step is removing the scaffolding-like supports. The process is simple but meticulous. It consists of using a flushing cutter and a scalpel to carefully snip off each contact point between the supports and the surface of the printed object.

Finishing of raw prints

SLA printers are known for creating parts with the smoothest surface finish of all 3D printing processes. However, because objects are made by stacking successive layers, 3D prints often have visible, horizontal layer lines. In addition, removing support touchpoints sometimes leaves marks and bumps on a part’s surface.

We remove imperfections, smooth edges, and get rid of support marks using traditional hand wet sanding. We start with a low grit sandpaper, and slowly move to finer grit levels over time until we reach the desired texture. For example, to sand the barrel of our pen, we use 4 sandpaper graduations, going from a 400 grit to a 2500 grit. Smoothing out a single barrel may take 30 to 40 minutes of work. To achieve the best surface finish, we had to try sanding multiple barrels before finding the perfect finishing technique.


After careful sanding, we finally clean the parts using mineral oil to remove tiny dirtiness that may remain due to sandpaper dust lodged in small cavities.


The final stage of the manufacturing process is the assembling step. To assemble all the parts of the pen we must first check that all the pieces fit together properly. Sometimes it is necessary to correct small dimensional inaccuracies so that the pieces assemble well. The overall compactness of the stylus is ensured by gluing the cap to the barrel.

Final result

In most people’s eyes, the final result of this project is a just another stylus. For us, it is a beautiful moment! Passionately creating the eT-pen with our hands became the way we found to contribute to this wonderful community of e-ink paper lovers. The eT-pen started as a personal endeavor that rapidly transformed into an incredible journey full of challenging and rewarding experiences. We hope you enjoyed discovering the multiples steps that we got to accomplish in creating the eT-pen. Thank you so much for your interest in this adventure! We loved to have you on board.

This is the final article of the eTrament project blog series. Our next step is launching the eT-pen. Sign up to our mailing list to be the first to know about the release date. Like you, we can’t wait to see it in your hands! We do our very best to make it available as soon as possible, but we are a small team; it’s just the two of us. Hence, it takes time: We had to learn everything from scratch, including building our website, preparing the online-shop, and organizing the fulfillment. So, stay tuned as it’s coming very very soon!

Audrey & Andrés

Stay tuned!

Want to be updated on the eT-pen release date?
Sign up to our mailing list to be the first to know.

Audrey & Andrés

Stay tuned!

Want to be updated on the eT-pen release date? Sign up to our mailing list to be the first to know.

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