This is a little base stand I made for the mac mini under the studio display. I have mine setup with the height and tilt adjustable stand but I'll also will made a similar variant for the just tilt adjustable stand. I added a little drawer on the side to store cables because there was some extra space and I thought it was a nice addition. 

I also made a video about this project here if you want to check this out: 

The one error of this is turning the mac mini on before you put the display on top but I always just left mine on so once I did that once I didn't really care about it afterwards enough to figure out a fix. But let me know if you have suggestions like a little prop mechanism or something