By Paul Vizzio
This design study explores how far modern desktop resin 3d printing can go toward creating a fully custom mechanical wristwatch. Using a Formlabs 3D printer, a purchased automatic mechanical movement and purchased watch hands, we designed and printed a case, crystal, and strap entirely from scratch — experimenting with ergonomics, tolerances, and functional winding mechanisms along the way.
Background and Goals
We’ve always been fascinated by mechanical watches — the precision, layering, and the way design meets motion. For this project, the goal wasn’t to reinvent the entire movement, but to design the surrounding architecture: the case, dial, crystal, and strap. The objective was to create a compact, ergonomic, and fully 3D printed housing around an existing skeleton mechanical movement, while experimenting with a new winding concept.
Two main design challenges guided the study:
- Size and ergonomics: Most watches are too large for my wrist. I wanted something closer to 30 mm, a size rarely seen today.
- Crown access: Traditional crowns are awkward to wind or set while worn. I wanted to integrate that function directly into the crystal.
Capturing Wrist Geometry
We began by 3D scanning my wrist and hand to establish real ergonomic data. This provided a 3D reference surface within CAD, allowing the case and bracelet curvature to match my actual wrist profile and helping visualize how different diameters would fit once printed.
CAD Modeling
All modeling was done in 3D CAD using direct measurements from the purchased movement, dial, and hands. With manufacturer drawings as reference, we built accurate mounting points and clearances. The design included:
- Case geometry and press-fit back cover
- Snap fit crystal with rack/gear mechanism along circumference
- Dial variations to reveal the skeleton movement
- Mounting points and strap design matched to my wrist scan
Each iteration was digitally tested to ensure proportion, balance, and comfort before moving to print.
3D Printing with Formlabs
The parts were printed on a Formlabs SLA printer using standard resin at 0.05 mm layer height for precision. The first print run included the case, crystal, and back cover. After printing, the parts were rinsed, cured, and cleaned of supports — a reminder that the finishing process can be just as time-consuming as the design itself.
Assembly and First Tests
Note to any aspiring or current watchmakers - we built this like brutes not using finger coverings and pressing harder than we should be. Do not follow our methods, we were just trying to figure out how everything works on this build. With the first set of prints complete, we press-fit the skeleton movement into the case. A small printed gear on the winding stem engaged with teeth around the outer crystal. The concept was simple — rotate the crystal to wind and set the watch — removing the need for a side crown entirely.
Installing the hands was a learning experience in itself. Without dedicated watchmaking tools, we relied on patience and fingernails to press-fit them into place. It wasn’t elegant, but it worked — the watch ticked, and that was enough validation for a first prototype.
Designing the Printed Bracelet
Next came the bracelet. Our first attempt at printing it as a single flexible piece resulted in a solid block — nothing moved. We then redesigned it as a series of interlocking links, printed individually and snapped together. After several tests, the strap finally articulated properly and wrapped naturally around my wrist.
A simple snap-fit clasp and snap style attachment completed the loop, connecting securely to the printed case.
Clear Crystal Finishing
For the crystal, we printed in clear Formlabs resin. Out of the printer, it was cloudy and textured, requiring extensive sanding and polishing. We started with coarse grit and progressed to 5000 grit, followed by polishing compound. The result wasn’t optically perfect, but it was impressively transparent for a printed component — enough to clearly see the hands and movement inside.
When assembled, the crystal rotated smoothly, winding and setting the watch exactly as intended.
Results
The final prototype demonstrated:
- A functional printed case, crystal, and strap built around a skeleton mechanical movement
- A rotating crystal winding mechanism replacing the side crown
- A comfortable, compact design tailored precisely to wrist geometry
While not a production-ready timepiece, the project validated that precision mechanical assemblies can be realized on a desktop resin printer when paired with thoughtful CAD design and iteration.
Takeaways
This design study was about learning through experimentation. Every phase — scanning, CAD, printing, polishing — reinforced the importance of iteration and material understanding. Future refinements might include improved sealing, more compliant strap joints, or UV post-cured optics for greater clarity.
At Vizeng, exercises like this are how we push tools to their limits — merging digital precision with tangible results.
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