The smaller the PC, the bigger the problems. That's what I've long believed in my many years of building relatively functional computers. You have to consider tolerances, sizes, form factors, and cooling more carefully when working within a tight space. Yet what surprised me about this mini PC build was how easily it came together.
What constitutes a mini PC these days has been somewhat skewed by various models of NUC and handheld gaming PCs—but I'd still count this Fractal Terra build as a micro machine.