comments:
Its tight, all my drives are 3.5" hard drives and there's about 3 inches between them and the motherboard pcb. I couldn't get a great picture to show you the space there. It is definitely tall enough for eight of them, that's actually my plan. You have to use a low profile CPU Cooler or an AIO, a regular Tower air cooler definitely would not fit. I found these awesome stackable hard drive holders on Amazon - https://a.co/d/05x4Ndra - they only kind of locked together, a little less secure than what Legos would be if that makes sense so if you go that route, make sure you pick them up from whichever one is on the bottom of the stack or you'll end up dropping everything below where you grab the stack.. ask me how I know.. You'll see in the picture that the bottom holders are a little over the edge, there's about an inch between that platform and the front glass so I use double-sided tape underneath the bottom holders to keep them from accidentally sliding.
These were often suggested years ago. They're okay but still pricey compared to 3d print to ship. https://www.amazon.com/dp/B07XYBKGWN