I designed the foot for this IO board:

https://www.amazon.com/dp/B07G13PDK1?psc=1&ref=ppx_yo2ov_dt_b_product_details

However, it can be adapted for any board you want to use. The one I have has 60mm spacing between the USB 2.0 ports and 20mm spacing between the audio jacks.

Note that if you are sourcing your own board, its advised to find a board with HD Audio, not AC97, and with USB 2.0 Ports, not 3.0. 

If you buy USB 3.0 ports, you won't be able to plug it into your motherboard since the USB 3.0 header is used by the case itself. 

As for HD Audio vs AC97, if the header plugs say “Audio” instead of “HD Audio”, its likely wired as AC97. Again, you want HD audio.

Foot shape credits to bloblob, original foot is here: https://www.thingiverse.com/thing:4970255

I am exploring a 15mm tall foot variant as well. If you don't see the files by Feb 2023, its not happening.