Custom numpad using an rp2040

A numpad which i can place next to my existing keyboard or remove depending on what im doing, it uses a RP2040 controller with QMK firmware.

BOM

Component	Quantity	Description	Link	Cost
MCU	1	Seeed XIAO RP2040	https://www.tinytronics.nl/en/development-boards/microcontroller-boards/others/seeed-studio-seeeduino-xiao-rp2040-dual-core-cortex-m0-separate-headers	€7.00
Switches	16	Cherry MX compatible switches	https://www.amazon.nl/mechanische-toetsenbordschakelaars-reserveonderdelen-reserveschakelaar-gamingtoetsenbord/dp/B0FH1J46V5	€9.79
Keycaps	16	DSA Profile (Blank)	https://www.amazon.nl/Paopaoldm-Engraving-Sublimation-Switches-Keyboard/dp/B0D3FR1HT5	€8.34
PCB	1	Custom Numpad PCB	https://cart.jlcpcb.com/quote?stencilLayer=2&stencilWidth=100&stencilLength=100&stencilCounts=5&plateType&spm=Jlcpcb.Homepage.1010Jlcpcb.Homepage.1010	€18.79
Inserts	4	M3 Heatset Inserts	https://www.bitsandparts.nl/Draadinzetstuk-M3-x-4-x-4-p1929600?gad_source=1&gad_campaignid=17339301268&gbraid=0AAAAADpItpeM5ppLxZ7FQfrTrApre5PML&gclid=Cj0KCQiA6Y7KBhCkARIsAOxhqtOuZc5zMjiW9-lEVaj6UW_oBEvaZ3dtExOxGxcrMgOVI5ki9B38r9saAgo3EALw_wcBAgo3EALw_wcB	€0.80
Screws	4	M3x16 Bolts	https://www.hornbach.nl/p/dresselhaus-lenskopschroef-kruis-m3x16-mm-phillips-ph2-din-7985-rvs-a2-100-stuks/6836143/	€0.18
Total				€44.90

I made a custom PCB with a 4x4 keyboard matrix and a rotary encoder so i can change my volume.

PCB Layout	Schematic

Name	Name	Last commit message	Last commit date
Latest commit super9chriss Update README.md Jan 24, 2026 f13665b · · Jan 24, 2026 History 13 Commits
CAD	CAD	update	Jan 24, 2026
Firmware	Firmware	update	Jan 24, 2026
PCB	PCB	update	Jan 24, 2026
BOM.pdf	BOM.pdf	Add files via upload	Dec 18, 2025
README.md	README.md	Update README.md	Jan 24, 2026