I guess it's a case mod rather than "scratch built" since I started with this:

HP DC7700 SFF

All the parts

Cannibalized Dell monitor stand, sheet metal from Lowes & Harbor Freight brake

Case fits together

Ports facing up for better airflow & wire management

Modded Supermicro RM PSU

This connects.....

To this for the monitor power

Plexiglas back with grouped HDMI/USB & Ethernet

Directed airflow to GPU's

ALL wiring out the back

Of course, I would do it differently the next time....