OK, I made a riser. It sits in the cross area of the bracket, with a clip on the top part. You can put 2 of those risers on it in any of those three positions, then clip on a second bracket. You can then mount a second drive. As I write this, I'm already thinking I may change the design a bit so you can stack as many as you like, so if you have a Quarda 950 or something with room for full height drives, you could stack 8 brackets and have an 8 drive RAID (you know, just because. )

[attachment=0]riser.png[/attachment]