The to40 is a 3D printable DIY keyboard that only has numpad, arrow, and navigation keys. Might come handy for laptops which typically have lackluster arrow keys, nonstandard layout and lack a numpad. 60% keyboard users might also enjoy it as they can place their mouse between the 60% and 40% parts.
The to40 uses a raspberry pi pico microcontroller and its firmware is implemented with KMK (CircuitPython).