This is a numpad that I made, it will fit any standard cherry/kailh whatever switch you want it is meant to use an arduino pro micro as the controller with QMK firmware installed on it, I handwired mine with kailh box navy blue switches after body shopping the case to be as close to a proper product as possible

Handwiring guide:
https://geekhack.org/index.php?topic=87689.0

Use the pins image for reference on this site:
https://kbfirmware.com/

with this layout pasted in:

[{a:7},"","","",""],
[{y:0.5,a:4},"Num Lock","/","*","-"],
["7\nHome","8\n↑","9\nPgUp",{h:2},"+"],
["4\n←","5","6\n→"],
["1\nEnd","2\n↓","3\nPgDn",{h:2},"Enter"],
[{w:2},"0\nIns",".\nDel"]

flash the hex file to the arduino after you make your keymap
https://beta.docs.qmk.fm/detailed-guides/flashing