I have designed a backplane in Mini-ITX format with Kicad and I have shared it as a GPL3 license, being the Open Source Hardware project. This backplane is initially intended to be used with Sergey Kiselev's Micro8088 or xi8088 PC clones, among others system powered by x86 architecture. However, other old systems could also be developed using FPGAs built or adapted to ISA or PC / 104 type slots, plus other accessories based on these.
Although I share the sources of the project, it is still in the prototype phase and could contain bugs that should be solved, being the PCB is 4 layers. It would be possible to design the MiSTer DE10-Nano addons adapted to PC/104 to save space and maybe even fit into Slim-type Mini-ITX cases, along with a Pico-ITX power supply:
More info in the project URL of my Hackaday account:
https://hackaday.io/project/175340-univ ... -backplane
Project sources on my GitHub:
https://github.com/spark2k06/Universal-ITX-Backplane
What do you think? Ideas or suggestions are always welcome.