The author remixed this model.
For the magnetic base I used a phone car magnetic holder that you can find here: https://a.aliexpress.com/_Ex3Fofw
To install the base, remove the rubber cover and unscrew the screw. Then screw it back in the new angled base. You may need a little bit m3 longer screw.
You can use my cable tie magnetic file to hold the USB C cable.
You have to use 8mm diameters, 2mm think magnets for the cable tie cable holder and for the USB C female base.
I made the back cover has thin as possible as well.