How to build a Patternflow

Patternflow is an open-source LED synthesizer played with four knobs. This piece is the route from nothing to a working panel. The parts to order are in https://ganpan.org/patternflow/parts, and what to do when a step fails is in https://ganpan.org/patternflow/trouble. The full written guide is the Build Guide in the repository, linked at the end.

Power: the one rule

On the PCB build, power the board through J4, the two-pin screw terminal on the back. Strip a USB cable, clamp the two wires in, tighten. On a v3.9 board it is the only power connector there is. A breadboard build has no J4; there the 5 V lands on the breadboard rail. The rule that holds on every route is the same one: 5 V never goes into the ESP32-S3 module's own USB ports.

Do not power the board over USB-C, in any arrangement. A v3.0 board powered through USB-C ran completely normally for 20 to 30 minutes, with no heat and no symptoms, and then began smoking at one of the connector pins, destroying the receptacle and the power path around it (issue #221). Whether that was a soldering defect on the tight-pitch pins or a structural limit of the part under the matrix's peak current was never settled, so v3.9 removed the footprint entirely. The failure is delayed, which is why passing a multimeter check and running for half an hour proves nothing.

On a v3.0 board, leave USB1, R1 and R2 unpopulated and do not buy those parts. The module's USB-C ports are for data only: flashing, and wired MIDI. So is the USB pass-through in the larger enclosure.

Which route

RouteWhat it involves
Custom PCB and 3D-printed caseThe documented main route: order the board, print the enclosure, hand-solder, flash from the browser
BreadboardThe same electronics on jumper wires, no custom PCB and no soldering iron. Treated as a real Patternflow, not a prototype: https://patternflow.work/build/breadboard
Other combinationsEnclosure and electronics are separate choices. The assembly map lists them: https://github.com/engmung/Patternflow/blob/main/docs/assembly/README.md
Buy one assembledAssembled units, DIY kits and custom enclosures have been offered through Crowd Supply. What is on offer now is on that page: https://www.crowdsupply.com/engmung/patternflow

Laser-cut and other enclosures are not an official path; community variants live in the repository under hardware/case/remixes/.

What it costs, as of September 2026

The build, in order

  1. Order the PCB. The PCBWay shared project needs no Gerber upload; any fab works if you upload the v3.9 Gerber zip instead. Do not order the v2.1 board — it is a different size and will not fit the v3 cases — and do not order anything from the experiment folder.
  2. Print the enclosure. A 256 mm bed prints bed_256mm/encloser.stl — body frame, back panels and panel mount in one file. A 330 mm or larger bed prints bed_330mm/encloser.stl as one piece with no bonding. Every build also prints the knob plate as its own job, black PLA against the body's white. Settings: 0.4 mm nozzle, 0.2 mm layer height, standard supports rather than tree supports, brim off. The Bambu P1S default profile works as it is.
  3. Bond the printed halves, right after printing. On the 256 mm print the frame and back panel each come in two halves, glued with CA glue straight off the bed, with masking tape holding them while they cure. A hairline gap at a seam is normal and fills with putty, or baking soda and CA glue. Let the glue cure while you solder.
  4. Solder the board. There is no written step list: the whole soldering process is one video, https://youtu.be/NZCjMBCsDAc. It was filmed on a v3.0 board, so the USB-C segment from 11:00 to 15:18 does not exist on a v3.9 board and is skipped. The module is never soldered; it plugs into two female sockets. The encoders insert from the back of the board, bodies on the back and leads soldered on the front. C11 has a polarity. Go over the joints with a multimeter, and leave the module unplugged until after the power check in step 6.
  5. Assemble the case. Seat the LED panel with its HUB75 IN connector toward the top; the fit is very tight, with near-zero clearance, so work it in slowly. Fit the panel mount and tighten its screws, then set the board into its bay and secure it by tightening the encoder nuts from the front. The power bank slides into a compartment behind the board bay. Video for this half, plus wiring and first power-on: https://youtu.be/J9C9bZgkNKs. It too was filmed on a v3.0 board.
  6. Wire it and power up. HUB75 ribbon from J1 to the panel's IN connector. J3 to the panel's power cable, polarity checked twice. The stripped USB cable into J4, red to +5 V and black to GND — thread it through the enclosure's cable hole first, clamp the wires, tug each one, and only then fit the board. Then, with power disconnected, continuity-check +5 V against GND at J3 (open is good), power up once and confirm about 5 V across J3, power off, seat the module per the silkscreen, and power on.
  7. Flash the firmware. The module is flashed on its own, off the board — if it is already seated, pop it gently out, flash it, and put it back. From the browser, at https://patternflow.work/pattern: desktop Chrome or Edge only, because it uses Web Serial, and nothing needs installing. Use the left USB-C port on the module, its native USB port, with a data cable. Wi-Fi is set up in the same flow. One firmware image serves every board generation, so there is no board selection to get wrong. Arduino IDE is the other route and uses the right port.
  8. Final checks. The panel shows Origin within a second or two. All four knobs visibly change it. A long press on encoder 4 opens the pattern list, encoder 1 brightness, encoder 2 the network screen. Power-cycle and confirm it boots with no RESET press. Then close the back panel, hooking the right edge in first and pressing along the snap-fit until it clicks, and press the knobs on last.

Both build videos show a lit panel. Patternflow displays rapidly changing light patterns that may trigger seizures in people with photosensitive epilepsy; anyone who feels discomfort should stop immediately.

Then fill it

The flashed image ships with Origin alone. The Basics pack on the community decks shelf installs 33 patterns in one click with no account: your browser fetches the pack and hands it to the board over your own Wi-Fi, so the board never talks to the internet itself. Making your own is https://ganpan.org/patternflow/patterns.

The full guide