snickerdoodle can be used as either a standalone prototyping board or combined with a pre-build, auto-detecting baseboard like:
breakyBreaky (0.1" header breakout board)
piSmasher ("SBC" with HDMI in/out, Gigabit Ethernet, USB, 68 reconfigurable I/O)
giggleBits (open-source, hackable Gigabit Ethernet router)
Great for reference designs or for building products.
Schematics, layouts, and more available on GitHub: https://github.com/krtkl