I bought a plastic tower for disks which let's me have 10 disks with some space between them. I then bought some Artic fans and attached them with tape to the 'tower'. Then I used a 11 years old optiplex 990 as Debian zfs connected to 8 of the disks, and I have 2 spares which I'll be able to use when the others die.
Performance is great. I could do it because I was given those disks for free, with plenty of ours on each of them.
Several hardware generations back, my old 4x160GB raid5 had two drives on the bottom of the case, held on by screws going through holes I drilled in the outer wall of the case.
These days I managed to snag a deal on a Supermicro 846. I'm still settling into it, the main thing that concerns me is being able to suck enough air through the drive bays without making a lot of noise. My previous incarnation used some iStar toolless drive bays. I've learned to appreciate hot-swap bays, mainly for only having to do the cabling once.