My mac mini application requires an external drive and a docking station, and to access the SD slot.  I worry that I will bump it and disconnect something, so these brackets and connectors are intended to solve that problem.

I don't expect you to print these parts and use them directly, as no doubt your accessories are different.  Modify the top part of the ‘support’ sketches in FreeCad/Ondsel to meet your needs, and set the ‘pad’ to 3mm or so for testing until you get the fit sufficiently tight.

My mac mini is a 2012 model, and I think several years use the same case design.  The 59mm clamp goes on the bottom, and the 78mm clamp goes immediately on top of the mac mini.