mfsbsd builds a custom live CD using an easily-customized Makefile. NanoBSD expects multiple partitions, some of which are mutable, so is more oriented toward booting small systems from flash.
For my purposes I needed an application server that would reboot to a known-good state, so I embedded the application code inside a mfsbsd live CD.
https://mfsbsd.vx.sk
I'm not able to find a lot of documentation on it. How does it compare to NanoBSD (and why did you choose it over Nano)?