This project provides a case that fits a standard 5.25" bay and contains two slim hot-plug laptop drive bays to insert CD/DVD and/or 2nd 2.5" HDD drive modules usually found in notebook PCs.

The idea for this project arose the lack of additional drive bays in modern SFF (small form factor) PCs, which usually only have a single half-height 5.25" drive bay occupied by the DVD drive.

As I often need to work with 2.5" hard disks from clients' laptops to copy/backup/mirror/inspect/salvage data, it is convenient to be able to connect 2.5" drives to the desktop PC without having to open the PC's case or to connect them via external cables and adapters.

Also, having the hard disk drive in an external drawer, allows the PC to be used by different people, each with his or her own disk drive, own operating system and own data.

Since most SFF PCs only have one 5.25" drive bay, I thought that it would be useful to create an 5.25" case which has two slots which can be used for either a slim laptop DVD drive and a 2.5" HDD drawer, or two 2.5" HDD drawers, to allow direct copying from one HDD to another.

The DVD drives and HDD drawers I use are from Lenovo ThinkPad laptops, so called "Serial Ultrabay Slim" devices. They use a slimline SATA connector, which has 13 pins composed of the standard 7-pin data part and a 6-pin power part to provide 5V DC to the device. Many other laptop manufacturers use slimline devices which have the same dimensions and the same SATA connectors, so that this project is not limited to ThinkPad devices. In particular, there are many "no-name" 2nd HDD slimline drawers that can be bought on eBay or AliExpress for less than 4 USD and which fit this project perfectly.

The dual slot case is composed of 5 printed pieces: 1 for each side (front, back, left right) and a separate plate on which the 6+7pin slimline SATA connectors are mounted. The position of this plate can be finetuned to exactly fit the SATA connectors on the inserted devices and the screwed on firmly to the back wall of the case. The front side part has a central grip cutout which allows to pull out easily the devices when changing them.

Slimline 6+7pin cables which consist of a standard SATA data cable and 2 power wires (black GND and red 5V) leading to a standard 4-pin IDE power plug are also available from eBay or AliExpress very cheaply (I paid USD 1.15 each, delivered). Two of these cables are needed, one for each slimline bay. If desired, the power wires of the 2 cables can be cut and resoldered to a single IDE power plug.

A tricky problem to solve was how to firmly attach the 6+7pin connectors to the connector plate. Of course, it would be possible to simply glue them to the plate with a hot glue gun. But I preferred a solution which allows clean disassembling if ever a connector need to be replaced. As the slimline SATA plugs have 1mm deep groove all around the rear plastic part, I use for each connector two bolts of 2mm diameter and 36mm length which are inserted into fitting holes the plate just above and below each connector. These bolts give a strong push/pull hold to the connectors, while leaving a bit of flexibility for small up/down rotations to match the corresponding male connector in the DVD/HDD device. For the bolts I used 2mm thick long nails from which I cut a 36mm long piece.

Ten M3 screws are needed for assembling the case: 4pcs M3x12mm for attaching the the front part to the side walls, 4pcs M3x10mm countersunk for attaching the side walls to the back wall and 2pcs M3x10mm with washers for fastening the connector plate to the back wall. In addition the case contains 4 screw holes on each side, at the same positions as used for 5.25" CD/DVD drives. I recommend to redrill all M3 outer screw holes with with a 3mm drill bit and all inner screw holes first with a 2.5mm drill bit and then cut the thread with an M3 tap.