4 layers

Sensei puck
PaoloJN/sensei-puck
Drop-in BLE water sensor puck. College proof of concept, archived before the first board order.
122 parts
Boards in 2 GitHub repositories, designed in KiCad, that use the MS5837-02BA by TE Connectivity (LGA-4(3.3x3.3x2) New Arrivals ROHS). See how each wires it, with its parts, size, README and files; the MS5837-02BA’s symbol, footprint and pinout are on its own page.

PaoloJN/sensei-puck
Drop-in BLE water sensor puck. College proof of concept, archived before the first board order.

jayis1/hardware-design-lab
Full-cycle hardware device designs — each device in its own subfolder with architecture, schematics, PCB layout, and software stack