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: parts/export/case/case_polykybd_split72_left_r7.stl (latest revision)
Right 3D-printed case	1	STL: parts/export/case/case_polykybd_split72_right_r7.stl (latest revision)
Spacer	2	STL: parts/export/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; see Keycap Stems
3D-printed key stems (1.25U)	14	SLA print recommended; see Keycap Stems
Transparent relegendable keycap covers (1U)	58	e.g. AliExpress relegendable keycaps
Transparent relegendable keycap covers (1.25U)	14	—

Three stem profiles are available — Flat, Stepped (in a sculpted and a uniform variation) and Curved. They all use the same 72 pieces, so the choice is only about feel. See Keycap Stems for the pictures, the plate filenames and how many of each to print.

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/export/display_holder/display_holder_r1.stl
Dummy display holder (if no status display)	2	STL: parts/export/display_holder/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

Printed extras

Neither is needed for a working keyboard — see Tenting Legs & LED Diffuser:

Part	Quantity	Notes
Tenting legs	8	One plate does both halves: parts/export/legs/legs_r2_8p.stl
LED diffuser frame	2	parts/export/diffuser/diffuser_frame_{left,right}.stl — one piece per half, holding all 36 diffusers. Requires spacer_diffuser_frame.stl in place of the plain spacer

Expansion slot

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 (recommended)	Cirque TM035035-2024-003 (35mm)	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 (smaller)	Cirque TM023023-2024-002 (23mm)	Same wiring; a smaller target for the same gestures

Caution

A trackpad only works on the right half — the firmware reads the pad there (POINTING_DEVICE_RIGHT) and its gesture zones were measured on a right-hand mount. See Trackpad.

Tip

Take the 35mm pad. The firmware is configured for it (CIRQUE_PINNACLE_DIAMETER_MM 35), and the gesture zones — the right-click corner and the dial ring — were fitted to corners measured on a 35mm pad. A 23mm pad still works, but it packs the same zones into a target barely a third of the area, and the fit was not measured on one.

Either pad needs a 3D-printed holder:

Pad	Holder	STL
35mm	Insert	parts/export/cirque_insert/cirque35_insert_r3_4p.stl
23mm	Slim / low insert	parts/export/cirque_insert/cirque23_slim_insert_r8.stl
23mm	High insert	parts/export/cirque_insert/cirque23_insert_high_r1.stl

All are in the PolyKybd hardware repo under parts/export/cirque_insert/; the _4p suffix means the mesh is a four-up print plate. The OpenSCAD sources (parts/cirque_insert/cirque35_insert.scad, cirque23_slim_insert.scad, cirque23_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).