Now that we have a SATA cable, the next thing we need for a hard drive in here is a SATA power cable.
Luck would have it I have a spare SATA power cable laying around from a dead power supply.
And 2.5" SATA hard drives are nice in that despite the 15 pin connector having positions for 3.3V, 5V, and 12V, the only required voltage for 2.5" disks is 5V!
And there's an internal USB port I don't care about RIGHT THERE!
✅ SATA data
✅ SATA power
Now we need somewhere to mount the drive. 24 gauge sheet metal is wonderful; it's like the hot glue of the computer modding world.
I don't know if this was the original intention for the standoffs I'm using. It's sure exactly-the-right-size for it...