One thing which may not be obvious from reading an article like this is the fact that building a case from scratch involves a lot of part assembly, test fitting, measuring, and disassembly. In other words it is not a simple 1, 2, 3... procedure. With that in mind, let's go back to the drive holder. Because of it's intended position and the design of the case, it would be impossible to fit the drives properly. Why? Well since the drive cage was to be suspended from the section dividing plate, once the holder had been screwed into position, access to the screws holding the drives in place would not be possible. Fitting the drives into the holder first would prevent it from being mounted in the case. Again, some thought was needed. There was no time to make radical changes to the case design.
I decided that using threaded mounting holes was the answer. First four 3mm holes were drilled in the top of the holder and corresponding 3.5mm holes in the top plate of the bottom case section.
After cleaning the metal around the holes, 3mm nuts were held in place with screws whilst they were soldered to the inside of the drive holder to form threaded holes.
Here is the bottom section top plate glues in place after all the required holes/slots had been drilled/routed. Now it was a simple matter of assembling the drives in the holder and then attaching it in the case with 3mm screws.
Here you can see the drive holder in place. The screws are black anodised to blend in with the dark Acrylic. The small white holes you can see in the divider plate are threaded to accept the motherboard mounting screws later. The second picture shows the drives from underneath. You will notice the top section of the case has been glued in place since this picture was taken during final assembly.