YOU CAN BUILD YOUR OWN SPLIT-FLAP DISPLAY THAT CLACKS LIKE AN OLD TRAIN STATION BOARD
Build a mechanical display that clacks through letters like an old railway departure board — 52 flaps per module, as many modules as you want.
by Scott Bezek
DisplaysHome
- difficulty
- ●●●●○
- time
- a weekend per module, weeks for a wall
- license
- Apache-2.0
- repo
- repo ACTIVE3,969 stars
●●●●○ · a weekend per module, weeks for a wall · Apache-2.0 · 3,969 stars · repo ACTIVE
WHAT YOU’LL NEED
- 3D printer + filament — printable parts — files are in the repo
- Electronic parts — full list with part numbers in the repo BOM
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
This is the split-flap project if you want one that actually works at scale. Scott Bezek has been refining it for ten years and the current design is production-ready: sensor boards that know when a flap is home, a daisy-chainable driver PCB (Chainlink) so you can run dozens of modules from one ESP32, and mechanical tolerances that survive months of clacking. The catch is that one module is a weekend, and a useful display is at least six modules — so this is a commitment. You will laser-cut acrylic, solder surface-mount components (the sensor board has an SOIC AVR and 0805 passives), and spend an afternoon per module on calibration. The 28BYJ-48 steppers are cheap and adequate, but they are also the noisiest part — if you want the sound, you will get it; if you wanted silence, this is not the project. The one thing most likely to go wrong is impatience: rushing calibration or using warped acrylic means flaps catch, and a jammed module destroys the illusion. If you have done a PCB project before and you want something that looks like it belongs in a museum, this is worth the weekends. If you have never soldered SMD, start with one module and see if you enjoy it before ordering parts for twelve.
IN THE REPO
NOT IN THE REPO
- —CAD files for laser-cut acrylic and 3D-printed parts are in the repository, with export scripts for common formats
- —Bill of materials exists with Digi-Key part numbers and links to AliExpress alternatives
- —Firmware is provided for both the module sensor boards (AVR) and the ESP32 controller, with PlatformIO configs
- —Extensive documentation covers assembly, calibration, electronics, and the custom Chainlink driver board
- —Licence is Apache 2.0 — fully open for commercial use
- —No pre-made PCBs or kits are sold; you order boards yourself from Gerbers or use the recommended fabrication services
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Partner · KickstarterBluHub reads and burns Blu-ray/DVD/CD, adds USB-C, USB-A, SD/TF and 10 Gbps data — plug and play, grand-piano finish.
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the repository README and the documentation in /docs (Start with 'Getting Started' and the BOM — the docs are thorough and you need to understand the Chainlink topology before ordering boards)
- 2.Order one sensor PCB and one Chainlink PCB from the Gerbers to test your soldering(Most people use JLCPCB or OSH Park; the files are in /electronics with detailed ordering notes)
- 3.Build one module end-to-end before scaling(Calibration teaches you what tight tolerances feel like, and one module tells you if you will enjoy making six more)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
Partner · KickstarterCORE POWER BANK S: 0.2" thin, 2.8 oz, 5000 mAh with 22.5W fast charging. Semi-solid battery, carbon fiber, IPX7 waterproof.
KNOWN ISSUES
- The sensor board is SOIC and 0805 — if you have never soldered surface-mount, practice on a cheap breakout first or order the boards pre-assembled from JLCPCB with their assembly service
- Acrylic warps with heat and humidity; store it flat and check each piece with calipers before assembly, because a bowed drum means flaps bind
- Calibration is per-module and takes 20–40 minutes if you follow the procedure; skipping it or eyeballing the home position means the module miscounts and gets lost
- The 28BYJ-48 motors are adequate but noisy and occasionally inconsistent; if you want a silent display, this is not the hardware for it (and upgrading to NEMA steppers means redesigning mounts)
- Chainlink boards daisy-chain, so one bad solder joint or one reversed connector can kill the whole string — test each board individually before chaining six together
- Vinyl letters or printed labels for the flaps take longer to apply than you expect; budget an hour per module for that alone
Can I build just one module to start?
Yes, and you should. The repository supports single-module builds with a simplified controller setup, and one module teaches you the mechanical tolerances before you commit to a wall.
Do I need to program the AVR sensor chips myself?
Yes, each sensor board needs firmware loaded via an ISP programmer (a $10 USBasp works). The repository includes PlatformIO configs and hex files.
Can I order pre-made PCBs or a kit?
No official kit exists. You upload the Gerbers to a fab house (JLCPCB, OSH Park, etc.) and order the boards yourself. Some PCB fabs offer assembly services where they solder the components for you.
How loud is it?
Audible. The 28BYJ-48 motors whine and the flaps clack — it sounds like a small train station, which is the point. If you need silence, this is not the project.
What if I do not have access to a laser cutter?
Use an online service like Ponoko or SendCutSend. The repository includes DXF files ready for upload, and both services ship cut acrylic.
Can I use a different motor?
The design is built around the 28BYJ-48 dimensions and gearing. Swapping to a NEMA 17 or a geared stepper means redesigning the motor mount and possibly the entire drum assembly.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
Scott's wall has 108 modules and took ten years to reach this level of refinement — every part is documented down to the Digi-Key number. How many modules would you actually build before you called it done?
Scott Bezek
Scott Bezek is a hardware engineer who started this project in 2015 and spent the next ten years refining it into a production-grade design. The current version is the fourth major iteration and is used in commercial installations. He maintains the repository actively and documents every change in detail.
Keep building — related projects
Same category, picked by how close they are to this build.
NO CAD FILESPut an old monitor behind glass and the mirror starts telling you the day
DisplaysHome●●●○○moderate
NO CAD FILESAn old discarded monitor becomes a mirror that shows your day every morning
DisplaysHome●●○○○starter
NO CAD FILESInkyPi — e-ink dashboard on Raspberry Pi (4.1k stars)
DisplaysHome●●●○○moderate
NO CAD FILESYour TV can light up the whole room with the colours of what is on screen
HomeDisplays●●●○○moderate
DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM1mo agoedited
Practical notes from our verification: this is one of the most thoroughly documented hardware projects we have catalogued — the /docs folder has assembly guides, calibration procedures, Gerber ordering notes, and even a structure for daisy-chaining dozens of modules from one microcontroller. The Chainlink driver board is the key piece that makes scaling possible, and it is a custom PCB you order yourself from the Gerbers. There is no official video walkthrough, but the README links to community builds and the documentation assumes you have built PCB projects before. The single biggest time sink is not assembly, it is calibration — every module needs its home position tuned, and rushing that step is how you end up with a module that drifts and jams.