I am making my own numpad circuit board! I purchased the case and made the circuit board.
Notes / Misc. Useful Documentation
Keycap Size, Spacing, and Alignment [link]
Guide on how to make a keyboard matrix [link]
Altium Multichannel Design [link]
Stabilizer
Cherry MX 2u key stabilizer [link]
Cherry Stabilizer Guide [link]
Potential LEDs
CLMVB-FKA-CFHEHLCBB7A363 [link]
RGB Chips
Cherry MX RGB SMD LED Position
Ideas for other boards
Bare PCB with feet [link]