All the empty space isn’t necessarily my choice, the case just doesn’t come in a smaller version. That said, it was really easy to build the machine when there’s enough space to maneuver :)

I came here to post this. These days with one or two M.2 slots on the mainboard and optical drives going out of fashion, cases could/should be vastly smaller.

If you're happy with an iGPU, the Lenovo Thinkcentre Tiny M75q with their 1 litre cases are very appealing. You can't really buy such small cases for DIY builds, unfortunately.

Airflow