Bill of materials and cost estimate

All prices are USD street prices observed in August 2026 and will drift. Part numbers and datasheets are in components.md.

An earlier revision of this project quoted $25–35 total. That figure left out the donor keyboard and palmrest, which are the largest single cost. The honest range is below.

Totals at a glance

Build path	All-in
Rev A perfboard + your own 3D printer	$90–130
Rev A perfboard + reused X240 base cover (hand-made route E1, no printer)	$110–150
Rev A perfboard + commercial print service	$115–170
Rev B PCB instead of perfboard	add $25–35 to any row
Tools, if starting from nothing	add $75–135, once

A. Donor hardware — every build

Part	FRU / spec	Qty	Est.	Source
X240 keyboard, US, with TrackPoint	`0C44020` non-backlit · `04X0177` backlit	1	$20–35	eBay, Amazon
X240 palmrest with ClickPad	`00HT393` (no FPR) · `00HT392` (FPR)	1	$20–40	eBay, iFixit
or palmrest + keyboard + ClickPad as one used assembly		1	$36–80	eBay
Subtotal			$45–75

Buy the backlit keyboard variant only if you want the backlight; the non-backlit 0C44020 has no LED strip and the backlight circuit is simply left unpopulated.

B. Controller and electronics — Rev A perfboard

Part	Spec	Qty	Est.	Source
Raspberry Pi Pico	RP2040, Micro-USB	1	$4	raspberrypi.com
(alt) Raspberry Pi Pico 2	RP2350 — verify QMK PS/2 PIO support first	1	$5	Pico 2 launch
40-pin 0.5 mm FPC → DIP breakout, with ZIF	bottom contact	1	$3–5	Tinkersphere, Amazon 2-pk
8–12-pin 0.5 mm FPC → DIP breakout	ClickPad, count your cable first	1	$2.70	Tinkersphere
40-pin 0.5 mm FFC extension, 150 mm		1	$2–4	BuyDisplay
74HC165 shift register, DIP-16	`SN74HC165N`	3	$4.26	DigiKey
10 kΩ bussed SIP resistor network, 9-pin	sense pull-ups	3	~$1	Jameco
N-channel MOSFET	`BS170` TO-92 (or `2N7002`)	2	~$0.50	DigiKey / Mouser
Resistors 4.7 kΩ, 10 kΩ, 100 kΩ, 100 Ω	¼ W	assorted	~$1	any
100 nF ceramic capacitors	X7R	6	~$0.50	any
1N4148 diodes	only if the three-key test shows ghosting	100	~$2	any
Stripboard ≈100 × 80 mm		1	$3–5	Vero
2 × 20-pin female headers	socket for the Pico	1 set	$1	any
M2 standoff + screw kit	brass, 6 mm	kit	$6–8	Amazon
30 AWG wire-wrap wire	assorted colours	1	$8	Amazon
1 mm foam gasket tape	self-adhesive	~1 m	$5	craft store
Subtotal			$40–50

C. Rev B PCB increment

Replaces the two breakouts, the stripboard and the wire. Everything else in B is still needed.

Part	Spec	Qty	Est.	Source
2-layer PCB ≈100 × 80 mm, 5 pcs	JLCPCB / PCBWay	1 order	$2 + $15–25 shipping	JLCPCB
40-pin 0.5 mm ZIF, bottom contact	Hirose `FH12-40S-0.5SH(55)`	1	$2.70	DigiKey
ClickPad ZIF, 0.5 mm	Hirose `FH12-nnS-0.5SH(55)`, `nn` from probing	1	~$1.45	DigiKey
74HC165, SSOP/TSSOP	`SN74HC165DBR` / `74HC165PW`	3	$1.35	DigiKey
SMD passives and 4 × 0603 resistor arrays		—	~$2	LCSC
Subtotal			$25–35

D. Enclosure route 1 — 3D printed

Item	Est.	Note
PETG, 120–180 g of a $20–25 spool	$4–6	Bottom case printed as two halves plus seven small parts — see `../enclosure/printed.md`
M2 × 3 mm heat-set inserts	$5
(no printer) commercial print of the split case	$25–45	Craftcloud, JLC3DP; the split is what makes a 309 mm case quotable

E. Enclosure route 2 — hand-made, no printer

Full detail in ../enclosure/handmade.md.

Variant	Est.	Note
E1 Reuse the original X240 base cover — recommended	$22–25	FRU `04X5184` / `00HT389`, labelled `SCB0G39215` / `AP0SX000I00` on the part. Already mates to the palmrest with the stock screw bosses; gut it, mount the board on adhesive standoffs, cut a rear USB slot. No CAD at all. eBay
E2 Laser-cut acrylic / aluminium sandwich	$30–60	Plates exported from the same OpenSCAD source; cut by SendCutSend or Ponoko
E3 Off-the-shelf sloped console	$50–60	Hammond 515-0950, 300 × 200 × 58 mm; the 309 mm deck overhangs 9 mm
E4 Plywood base + hardwood frame	$10–20	Saw, drill, finish

F. Tools — one-time, if not owned

Tool	Est.
Digital calipers	$15–20
Temperature-controlled soldering iron + fine tip	$25–60
Multimeter with diode mode	$15–25
8-channel USB logic analyser (FX2 clone)	$10–15
Flush cutters, tweezers, flux, solder wick	$10–15
Total	$75–135

OpenSCAD and KiCad are free.

Where to buy

DigiKey / Mouser — 74HC165, MOSFETs, Hirose connectors, resistor networks, passives.
Tinkersphere / Amazon / AliExpress — FPC ZIF breakouts, FFC extensions (AliExpress is cheapest and slowest).
raspberrypi.com approved resellers, Adafruit, Pimoroni — Pico.
eBay / iFixit — donor keyboard, palmrest, base cover.
JLCPCB / PCBWay — Rev B board; LCSC for its SMD parts in the same order.