The bottom cover is open (without a solid base) with feet for improved ventilation, which reduces the overall case temperature. The feet have notches designed to hook onto the bolts of a VESA mount.

I was off by a couple of millimeters on one side, but it’s almost unnoticeable. The corner mounting holes need to be made by yourself

It might be useful to someone, or someone may further develop this idea.

My minipc - Ren5000. But body the same I think