what a nice design!
what i wanna say is please keep consider using 3.5 hdd...
cz there's no much choice in sff cases that can use 3.5 hdd and i know
users who chases sff don't much like 3.5 but the speed between 2.5 and 3.5 has too much gap so i can't let it down.
hope this project goes well!