New improvements!

A new HDD cage design!
I use HP Proliant G8 Non-Hot Plug Drive Tray, Which is quite cheap to buy in ebay.
And retains the hot-swap function.

To install the drive, simply slide it in and press down on the clips to connect the power and data.

HP part number : 652998-001

Currently PCIe Part has not been added, I want to keep the height of the motherboard Part, and in the future I want to try to use the PCIe extension cable to turn 90 degrees to install it.

Currently using a small SATA Card and removing the Bracket.

This is a Modular Computer Case V2 remix for NAS.

After several modifications, now you can install 4 HDD, 2 SSD (but a little difficult to install), PCIe part is not yet designed.

A 12mm fan can be installed on the back side. But because of the HDD backplane can only be installed on the outside.
It is recommended to use a high pressure fan to facilitate HDD cooling.

The back of the hard drive cage uses a SAS to SATA adapter and two M3 stainless steel rods (I don't know what they are called in English, but they are usually used with linear bearings)

I had to put the SSD in the space above the HDD because the Sata cable was too difficult to install. Maybe using a thin SATA cable will make the installation less difficult.

The screws you need are:

1. M3x6x4.5 mm Threaded Inserts
2. M3x10 flat head screw
3. M3x6 flat head screw
4. 6-32 UNC computer case screws

Future Improvements:

1. Low-Profile PCIE slot