This is a case design for the Porcupine PCB, but only supports the 5x3+4 version with four thumb keys. The top fastens to the bottom via 6mm x 3mm magnets.
Magnets: https://www.amazon.com/DIYMAG-6x3mm-Refrigerator-Premium-Brushed/dp/B07KZQGWNN
The author marked this model as their own original creation.