Old PC Case for more HDD Storage

Hi All, after adding my 6th HDD to my Home setup Freenas - I'm now running out of room and gotten to thinking, could I utillise an old PC Case and Power Supply I have hanging around to Power some other Sata HDD's as an External HDD Chassis? I can then route the data SATA cables back to the base Freenas (would have its own dedicated SATA controller in there). This could then give me some storage expansion?

I appreciate I would have to modify the Power Supply switching in the External PC Case...

Old PC Case for more HDD Storage