This design is a remix from Lee Smith's ZX Mechtrum case. Uploaded my remix here with his permission.
https://leesmithsworkshop.co.uk/products/zx-mechtrum-3d-files-digital-download
It is a case for the ZX81Plus38 with cherry-type switches mechanical keyboard.
https://revspace.nl/ZX81plus38_simple_to_build_ZX-81_clone
https://github.com/mahjongg2/ZX81plus38
Please note that thi enclosure is not compatible with the original ZX81 board. It can be made compatible, but significant redesign would be required,
I used the following key switches:
The Brown ones.
These are they keycaps:
I made the key decals cutting one of these TS1000 Overlays from RWAP Software:
https://www.sellmyretro.com/offer/details/61441
You can order the keyboard PCB here:
https://www.pcbway.com/project/shareproject/ZX_Spectrum_Keyboard.html
The author remixed this model.