Update: I added the newest version v6 which adds the functionality to mount 80mm fans to the side(s) for cooling the drives. To mount fans, every other mount needs to be a fan version, since there is a drive every 40mm, and fan pins every 80mm. Simply press the standard 80mm fans onto the pins. It may take a bit of work to get them on, so be careful not to break the pins off.
Each mount is taller than v4, which means there is more space between the drives compared to v4. The tabs that contain the holes for the screws on v6 are shorter than v4, so they are not compatible with each other. The base has been updated to fit the new size, and I've only included the full rectangular base since it is the most stable. I've also updated the top mounts, and added one that has fan pins.
As shown in the picture, I have stacked 7 drives and it is still quite stable. It has a bit of flex, but there is no fear in it tipping over.
This is a minimalist rack mount for multiple 3.5 inch hard drives to stack vertically. Each section of the bracket lines up with the section above and is held together by the screws that go into the HDDs. The top version of the bracket does not include the struts so there is no wasted plastic for the drive at the top of the stack.
The normal bracket has overhangs at the top of the struts where the screw hole is, so be sure to print with supports. Filing/sanding off the supports will be required after printing, but the marks will be hidden when attached together. The top version of the bracket has no overhangs.
Once the screws are in all the way, it is a very sturdy setup. I have stacked 4 drives and there is almost no movement when applying pressure laterally, so it could safely hold at least 5 drives.
Edit: I've added a couple base designs that will provide a bit more clearance between the bottom drive and the surface it sits on. Both print without supports