This design is a modular HDD rack system that allows for flat printing and can be assembled in any number of drives you'd like. I've also designed a backplane to allow for hot swapping of drives and outputs to a SFF-8087 connector to reduce the cable complexity. 

I've used this design of HDD cage in all of my NAS PC designs, but was originally designed to be a rack for a Powermac G5 conversion case. Super modular, pretty sturdy design and assembles together with 6/32x3/8" screws.

There's plenty of space between drives to allow for decent airflow through the cage and uses off the shelf rails that are plentiful on Amazon and AliExpress for the drives themselves.

The updated V2 backplane is designed to work with many different power input configurations. There's a couple of standard SATA Power connectors, a rising clamp cage screw terminal connector, JST-XH Connectors and standard DC barrel jacks. Not all power inputs support the 3.3v and 5v rails required by the SATA standard so I've added a spot to screw in and connect an off the shelf 25W 5V DC-DC switching converter so this backplane can be used for single supply configurations. 

Additionally, a lot of server and surveillance drives have implemented 3.3v power input as a shutoff signal so while that rail is routed on the backplane, it remains disconnected and can be connected with a jumper on the back side of the board with a drop of solder.

V2.0 Backplane in both HBA and SATA Breakout compatible

Dimensions:

40x119x165mm (Each Drive)

37.75mm Drive Spacing