The schematic, KiCad design files, and Gerber files are all released under the Creative Commons Attribution license. For the base station, the board is assembled with the headers, C17, C18, C20, and U5 installed; additionally, the solder jumper is bridged, and pins 23 and 24 of the NavSpark header are bridged. The device is then powered through the NavSpark’s USB port. For the rover, all the components are installed, but the solder jumper isn’t used, and no pins are bridged. The device is then powered through the adapter board’s USB port, and both serial data streams are connected through the FTDI FT2232H chip. This way, only one connection is needed to the rover computer. For convienence, here is a Mouser part list.