Frequently asked questions
Honest answers to the questions that come up most often about building, sourcing, and running split flap displays.
Cost & Difficulty
How much does it cost to build a split flap display?
A single module costs roughly €15–90 in parts, depending on the motor and case you choose. Every figure on this site, including the display planner, prices parts only: your own assembly time isn't in it, and neither is anything bought ready-assembled.
| Build path | Parts cost per module |
|---|---|
| Minimal (28BYJ-48, 3d-printed case, 3d-printed flaps) | ~€15–30 |
| Mid-range (NEMA17, 3d-printed case, 3d-printed flaps) | ~€30–40 |
| Finished (NEMA17, sheet-metal case, screen printed flaps) | ~€80–90 |
A four-character display runs roughly €60–360 in parts, depending on which path you take.
Ordering modules assembled costs more than the parts and is quoted per project, since flaps, case, power supply and shipping depend on the build. Either way it stays well under the commercial alternatives, which start at ~€1,000 (Vestaboard) and scale to €10,000+ for custom installations from specialised vendors.
How hard is it to build?
Intermediate. If you've assembled 3D-printed parts and connected a microcontroller before, you'll be comfortable. Specific things that are not required: soldering, programming, a laser cutter.
The main variable is 3D printer calibration — flaps need to come out at 0.3–0.6 mm total thickness. A well-tuned printer makes this easy; a poorly tuned one will cause problems.
First build takes 45–90 minutes per module. Subsequent modules are faster.
There's also an active community on discord, supporting the build journey for every maker.
What tools do I need?
- An FDM 3D printer (any bed size that fits the parts — roughly 150×100 mm minimum)
- M3 screwdriver or hex key set, as well as a small philips driver for the NEMA module.
- A 12V power supply (any 12V, 2A+ supply works for a single module)
That's it for a minimal build. No soldering iron, no oscilloscope, no laser cutter.
Motor & Parts
Which stepper motor should I use — 28BYJ-48 or NEMA17?
Start with a 28BYJ-48 if you want the cheapest build (~€3) or are just testing. It produces a working display and is available everywhere.
Upgrade to a NEMA17 (specifically model 17HS08-1004S — the 20 mm height, lead-only version) for faster, more reliable motion. This is what the displays on the flip forward YouTube channel use. Cost is ~€8–12 per motor; Stepperonline ships to Europe at scale pricing.
The 20 mm height matters: taller NEMA17s won't fit inside the drum.
Do I need a laser cutter?
No. The flip forward design is fully 3D-printer-first. All structural parts print without supports. For permanent installations, the cases can be ordered as powder-coated sheet-metal — but that's optional, not required.
Can I print everything on a standard FDM printer?
Yes. PLA and PETG both work. All parts are designed to print without supports at 0.28 mm layer height. The flaps are the only precision-critical prints: they must be 0.3–0.6 mm thick, which requires a 0.15 mm layer height and well-calibrated first layer.
Firmware & Control
Does the firmware need to be programmed?
No. The controller PCB ships pre-flashed. On first power-up, the module broadcasts a WiFi network called "flip forward". Connect from your phone or laptop and the setup page handles homing and configuration. No IDE, no uploads, no code.
How do I control a split flap display?
Three ways, all free, all speaking the same simple command protocol:
- The module's own web UI. Every module serves a minimal page over WiFi for homing, alphabet setup and setting a character. No app, no account, no internet.
- play.flipforward.de. The easiest route once a module is paired with your WiFi: multi-row displays, images, alternative alphabets, and remote control over MQTT from anywhere. Virtual twins and hardware displays behave identically, so you can build and test a display before you own one.
- local-control. An open-source desktop app for macOS, Windows and Linux that finds every display on your local network via mDNS/Bonjour. It also does firmware updates, live logs and guided calibration, and works with no internet connection at all, which is why it's become the most-used option for permanent installations. Installers are here.
You can also send commands via HTTP POST from any HTTP client (curl, Postman, Home Assistant, etc.). Full detail on Controlling Displays.
Can a display cycle through several messages?
Partly. local-control can send several messages that rotate on a repeat interval, and a module keeps its configuration through a power cut and comes back up without anyone touching it.
What doesn't exist yet is a saved playlist: a named sequence you can store as a file, reload later and hand to someone else. That's next on the list. For content that changes on a schedule today, push it in from outside via the webhook endpoint.
Can I customize the character set?
The standard set is 43 characters: A–Z, 0–9, and a handful of symbols (€ . ? ! - :) plus a blank. The homing firmware learns positions by asking which character is currently visible, so you can print a custom flap set with any alphabet and the firmware adapts. The 3D-printable flaps are designed in the typeface Oswald, but the .3mf files can be modified.
What size are the flaps, and can I have them printed instead?
Flaps are 44 × 30 mm plus material for the hinges. That one isn't adjustable, because the whole hardware design is built around it.
They finish at 0.3–0.6 mm thick either way, printed or cut from plastic sheet (polypropylene works well). Flaps have to flex for the display to work reliably, and a 1 mm sheet is far too rigid. UV printing and screen printing both work. The hard part is sourcing white on black, so ask for a sample before committing to a run. The flaps page has the detail.
How many flaps fit on one module?
The standard alphabet is 43 characters, and 52 is the highest count I've tested.
There's a minimum too, which catches people out. Below roughly 30 flaps the topmost flap loses the pre-tension it needs to fall cleanly, so if your display only needs ten characters, repeat them until the drum holds at least 30.
Can I build a colour or pixel display?
Yes. Fill the drum with solid colours instead of characters and each module becomes one large mechanical pixel. Stay above the 30-flap minimum (six colours, printed five times each) and you get a useful side effect: with every colour repeated around the drum, the nearest instance is never far away, so a colour change completes in well under a second.
Can it show a clock or live data?
Yes. Unlike a flip clock, a split flap module is addressable, so clocks, countdowns, arrival boards and dashboards all work. Program the content directly, or push updates to your display's webhook endpoint from whatever system has the data.
Scaling Up
How many modules can I chain together?
As many as you like. The serial daisy-chain protocol has no firmware module limit. In practice: inject power every 5 modules (each module draws up to 500 mA; the chain is rated at 3A continuous). A 20-character display needs 4 power injection points.
What does a full installation look like?
Modules snap onto a backplate via the back case mounting holes. For larger displays, a metal rail system keeps everything aligned. The connector boards that link modules handle both power distribution and serial communication — there are no loose cables between modules.
How much does a module weigh?
Roughly 400 g, with a metal case and a NEMA17 motor. A 26-module display is about 10.4 kg of modules before the backboard, case and power supply. For anything larger, it's the mounting surface rather than the modules that needs thinking about. The module front face is 116 × 60 mm, and the specifications page has the rest of the numbers.
Do the modules need ventilation?
No. Under continuous heavy use they stay below 38 °C, so no ventilation slots and no active cooling. Do leave 3–5 mm of clearance above the modules, and avoid a fully sealed cavity behind the display where warm air has nowhere to go.
What happens if one module fails?
Power faults are contained. Each injector board isolates at most five modules behind its own eFuse, so a short or an overcurrent shuts down that group and nothing else.
Signal is a daisy chain, so a module whose controller fails outright stops relaying commands and everything downstream of it in that chain goes quiet. Modules upstream, and every other chain, keep running. Any module can act as a WiFi entry point, so a long row can be split into several shorter independent chains: ten chains of ten means one failure takes out ten modules instead of a hundred.
A mechanical failure, a jammed drum or a bad flap set, only ever affects that one module.
Can I pull a module out from the front?
Not yet. Modules are screwed to a backboard through three holes in the back case, so today a module comes out from behind. Front extraction, with the connector boards doubling as the retention mechanism, is in development. If you're planning a recessed installation with a permanently closed back, get in touch before you build. Planning an Installation has more.
Comparing Alternatives
How does flip forward compare to scottbez1's splitflap project?
Both are open-source DIY split flap display projects, and both work well. The differences:
| flip forward | scottbez1/splitflap | |
|---|---|---|
| Structure | 3D-printed + sheet metal option | Laser-cut MDF or acrylic |
| Lettering | 3D-printed multicolor flaps | Vinyl stickers |
| Controller | Custom PCB (ESP8266) | Custom PCB (ESP32) |
| Firmware | Pre-flashed, WiFi setup + MQTT | Open source, requires flashing |
| Best for | FDM printer, no laser cutter | Laser cutter access, full open source |
If you have a laser cutter and want maximum openness, Scott's project is excellent. If you have an FDM printer and want a polished out-of-the-box experience, flip forward is the better fit.
Why not just buy a Vestaboard?
Vestaboard is a finished product starting at ~€1,000 for a small unit. It's a real split flap display and the fastest path to something on your wall with no building involved. flip forward is for people who want to build it themselves — because of the process, the price, the customizability, or because they want a display size that Vestaboard doesn't offer. The two aren't really addressing the same audience.
What's the difference between a split flap display and a flip clock?
A flip clock cycles through a fixed sequence (hours and minutes) in one direction, forever. A split flap display is addressable — it can jump to any character in its alphabet on demand. This requires a home sensor (a hall effect sensor detecting a magnet in the drum) so the firmware knows where the current position is and can motor to the right character. Flip clocks don't need this because they always move forward.
Sourcing in Europe
Where can I buy parts or kits in Europe?
The flip forward shop at shop.flipforward.de (launching soon) will sell PCBs, hardware kits, and flap sets — all shipped from Germany. No customs fees for European buyers.
In the meantime:
- All 3D models and documentation are free to download
- Stepper motors and hardware are linked with European suppliers in the Sourcing guide
- Sample kits are available on request via the Discord server
Can I buy assembled modules instead of building them?
Yes, and for installations that's usually the sensible route. Assembled modules, connection boards and injector boards can be ordered directly by mail at hello@flipforward.de while the shop is being set up.
Quotes are per project and net of VAT. Everything around the module varies: flaps (especially with a custom alphabet), the case, the power supply and shipping are quoted separately, because they depend on what you're building. Tell me the module count, the alphabet and roughly when you need it, and you'll get a number back.