I have been working on the Mount for the caddy and the ears to attach the whole thing to the rack.
The Blade center will be 3U, that fits perfectly. However I could not make 8 H2s in 3Us for a very few millilitres.
Unfortunately the audio connectors are very tall, 4mm taller than the other connectors, which times 8 is 32 millimetres.
Finally I decided to make an unusual hack, letting each audio connector embed in the next block:

- H2Mounted.PNG (276.85 KiB) Viewed 8885 times
The Audio block is higher than the mount, as you can see on this side view.

- H2Mounted2.PNG (105.7 KiB) Viewed 8885 times
However, a socket has been created on the base of the mount to embed the audio connector from the previous H2 block.

- H2Mounted3.PNG (168.14 KiB) Viewed 8885 times
With this hack it seems possible to fit 8 H2s in 3Us.
Also, note that the mount has been created in a way that no support should be required to 3D print it, which will save time and plastic.
Little knobs and holes have been created to ensure good alignment.
Here you can see how each audio connector embeds in the next block, saving space to allow 8 units in 3Us.

- H2BladeCenter4.PNG (116.18 KiB) Viewed 8885 times
Once you put them toguether the blade center looks like this:

- H2BladeCenter.PNG (123.25 KiB) Viewed 8885 times
I am going to be printing this weekend to test if all the parts work as expected.