This is my first design made / completed with Tinkercad.
I found a few other drive brackets and item on Thingverse, but they did not suit.

I made a full width tray for the 5.25" drive bay (typically found in PC cases), which will allow you to mount a 3.5" Hard Drive. The design has very good air-flow for maximum cooling.
The base strips on the bracket are only 1mm thick, so the will sag under the weight of the HDD. This in turn provides a clamping action for the retaining tags on the top of the bracket - to help hold the drive. I also made the design with 2 flexible retaining tabs at the rear of the drive holder. This allows the ability to add/remove the drives without necessarily using mounting screws.