This is a very cheap macropad(4 usd) you can use for typing your emails or passwords.
It has USB C
Components used:
RP2040 Zero(from Waveshare or chinese copy)
https://a.aliexpress.com/_EQsV7VT

4 key flexible nupad
https://a.aliexpress.com/_EJjBgLL

maybe some glue and hot glue
Will be adding links soon.

Probably any small dev baord such as arduino nano or mini esp would fit but i did not test. I made it specificaly for the rp2040 zero as they have usb C

The code you upload with arduino IDE
Here is the code and schematic on the github page: https://github.com/AllexRaresh/MacroPad

Print at  0.2mm layer height 

There are 3 versions of the base:

Ultra slim(good luck)

Normal version(for the version with unsoldered pins)

Taller version 

There are 2 versions of the Top:

Normal(hollow, less fillament, more space)
 

Filled(worse)

You have to glue the PICO upside down so that the usb c goes trough the hole

I recommend using the taller version to have more space for the cables.

Will add better versions after feedback