I originally came across this project but wanted to have the visible screw holes and a mount on the back.

Uses this multiclip system from here - https://www.printables.com/model/44003-multiclip-universal-object-mounting-system

Required hardware:

• 4x M3 x 5,7 heatset inserts
• 2x M3 x 3,0 heaset inserts
• 4x M3 countersunk head screws (10mm)
• 4x M2.5 button or cap head screws (5-8mm)
• 2x M3 button head screw (4-5mm)

Running this software: https://github.com/kormax/apple-home-key-reader