Parts List

This page lists every part needed for a complete PolyKybd Split72 build.

Required parts

PCBs

Part	Quantity	Notes
Left PCB (assembled, 4-layer, 1.6mm)	1	See PCB ordering
Right PCB (assembled, 4-layer, 1.6mm)	1	See PCB ordering

Mechanical

Part	Quantity	Notes
Left aluminum plate (1.2mm)	1	Order as 1.2mm aluminium PCB
Right aluminum plate (1.2mm)	1	Order as 1.2mm aluminium PCB
Left 3D-printed case	1	STL: case/case_polykybd_split72_left_r7.stl (latest revision)
Right 3D-printed case	1	STL: case/case_polykybd_split72_right_r7.stl (latest revision)
Spacer	2	STL: case/spacer.stl
M3×10 hex screws (rounded head)	8	—
M3 hex nuts	8	Required for case revision r4+

Note

If you use CNC aluminium cases instead of resin-printed ones, add threaded inserts to the screw holes. Resin prints accept M3 screws directly.

Tip

If a resin case is slightly warped, use a hair dryer to soften it, then press it flat under a heavy object — it really works.

Switches & keycaps

Part	Quantity	Notes
MX-compatible key switches	72	See Compatible Switches
3D-printed key stems (1U)	58	SLA print recommended
3D-printed key stems (1.25U)	14	SLA print recommended
Transparent relegendable keycap covers (1U)	58	e.g. AliExpress relegendable keycaps
Transparent relegendable keycap covers (1.25U)	14	—

Key stem profiles available: Flat (R3), Stepped (R2), or Curved (R1–R5). See the build guide for quantities per profile.

Displays

Part	Quantity	Notes
0.42” OLED displays with FPC	72	Must be 14-pin; see Displays & FPC Extension
0.96” status displays (FPW096W001Z0)	2	Optional; ~40mm FPC cable
Status display holder	2	STL: parts/display_holder_r1.stl
Dummy display holder (if no status display)	2	STL: parts/display_holder_dummy_r1.stl

Cables

Part	Quantity	Notes
Short USB-C to USB-C cable	1	~50cm, connects the two halves
USB-C to USB-A or USB-C cable	1	Connects to the host computer

Note

A USB-C to USB-A cable + USB-A to USB-C adapter combination only works in one orientation. Use a native USB-C to USB-C cable to avoid confusion.

Optional parts

Caution

Each half has a single physical expansion slot, and only one part can occupy it per side. You can still fit a different one on each half (e.g. the sensor on the left and a trackpad on the right). Decide which one you want per side before you start.

The slot is one mechanical space served by three separate electrical connections — they are not variants of one connector:

Part	Connects to
Light + proximity sensor, trackball	The labelled 5-pin footprint 3-6V / SDA / SCL / INT / GND
Rotary encoder	Its own footprint in the same space, on different pins
Cirque trackpad	A 12-pin FPC running to J37 — a flex socket on the back of the PCB

Rotary encoder

Either of these fits the PCB footprint:

• EVQWGD001 — Note: remove the last pin before soldering. This encoder is no longer in production.
• Alps EC11 encoder

Pointing devices (choose one)

Option	Part	Notes
Trackball	Pimoroni Trackball	Solder header without the plastic distance holder
Trackpad (small)	Cirque TM023023-2024-002 (23mm)	Remove R1 on back to switch to I2C; needs 12-pin FPC ~50–70mm, running to J37 on the back of the keyboard PCB
Trackpad (large, experimental)	Cirque TM035035-2024-003 (35mm)	Modify OpenSCAD source before printing the holder

The 23mm trackpad needs a 3D-printed holder — pick the height that fits your build:

Holder	STL
Slim / low insert	parts/cirque23_slim_insert_r8.stl
High insert	parts/cirque23_insert_high_r1.stl

Both are in the PolyKybd hardware repo under parts/. The OpenSCAD sources (parts/cirque23_slim_insert.scad, parts/cirque23_insert.scad, and the experimental parts/cirque35_insert.scad) are there too if you want to adjust the fit.

Only one pointing device can be installed per half.

Ambient-light + proximity sensor (highly recommended)

Option	Part	Notes
Light + proximity sensor	Pimoroni LTR-559 breakout	Plus a 5-pin 2.54mm pin header. Solders to the sensor’s own labelled 3-6V / SDA / SCL / INT / GND footprint on the Split72 PCB — a separate connector from the encoder and pointing-device connectors in the same expansion slot.

With the sensor fitted, the keyboard drives keycap brightness from the measured light level and wakes the displays when your hand approaches — see Display Brightness. It is optional in firmware (a clean no-op when absent) and side-agnostic. Split72 only — the Split42 has no expansion port.

Caution

The sensor must be soldered before the plate goes on — it does not fit through the plate hole, so it cannot be added later without an almost complete disassembly. Fit it as the very first assembly step (see the Step-by-Step Build Guide).