This looks like it's supported by a 3D printed enclosure. Otherwise I agree - you need >2.0mm thick PCB to prevent falling out and these are not offered by the usual cheap low-volume PCB manufacturers.
Doing plastics is well outside my skill set, so it was awesome to see him do that! xobs posted about the case here -> https://www.crowdsupply.com/sutajio-kosagi/tomu/updates/fina...