Files here: https://iomixer.com/pcba
Bootloader and firmware: https://iomixer.com/releases
Other links and miscellaneous info: https://iomixer.com/prototypes
I use JLCPCB but I'm sure this would work just as well with other PCB assembly services.
If anybody does make some you'll need to contact me about the activation, there is no purchase page yet.
([email protected])