NZXT H1 3.5 inch hdd bracket mount
I needed my existing 4TB HGST hard drive mounted securely inside the NZXT H1 but didn't want to drill holes onto the case.
Materials:
x4 3.5 inch hdd screws
[reuse] x2 original screws from the 2.5 inch hdd caddy
[optional] x2 power supply screws
Notes:
When mounting, pay close attention to the front/top inside of the case where the front IO pcb is, make sure to not damage it. Then, once mounted, the hard drive pokes out slightly in the rear. I have not tested it with the rear extension fan mods available out there so fyi.