Finally, it looks like someone has made exactly what I need. A trayless 4-bay Thunderbolt enclosure.

Triple Thunderbolt | USB3.0 | eSATA hardware raid/jbod enclosure with five drive tray-less (http://www.datoptic.com/hardware-raid-jbod-enclosure-with-thunderbolt-usb3-0-esata-five-drives.html)

It's a bit pricey at over $700. But, given that I have a pre-USB 3.0 MacBook Pro, my only options are this or wait for the Belkin Thunderbolt Dock and couple it with a USB 3.0 enclosure.

I'm curious if anyone has experience with this. Or am I going to have to be the guinea pig?

I wish someone released a Thunderbolt enclosure for just one 2.5" drive. Getting one with a SSD is ridiculously expensive... I guess an empty TB enclosure would be expensive too, though :/

Check this out:
http://www.elgato.com/elgato/na/mainmenu/products/ThunderboltSSD.en.html

Might not be what you're looking for. But it is possible.

I would only buy a drive with two thunderbolt ports. The ability to pass through is a must in my book - my MacBook Pro with only one thunderbolt port that is.

Check this out:
Elgato Thunderbolt? SSD - Portable High-Speed Drive (http://www.elgato.com/elgato/na/mainmenu/products/ThunderboltSSD.en.html)
Might not be what you're looking for. But it is possible.
I want an empty TB enclosure... The ones that come with SSDs are so overpriced it's rediculous. And Elgato is the most expensive brand offering them that I've seen. At least here in Sweden.

I would only buy a drive with two thunderbolt ports. The ability to pass through is a must in my book - my MacBook Pro with only one thunderbolt port that is.
I have the retina MacBook Pro which has 2 thunderbolt ports. And with current prices I'm happy if I can afford just one tb device ;)

What about the Seagate adapters? The 2.5" version will work with any 2.5" drive including a SSD. I use the desktop 3.5" version and love it. I bought one thunderbolt device and can use as many 3.5" drives as I want. I would never buy a single thunderbolt drive since they are a complete waste of money.

I do use the FW800 seagate adapter for 2.5 drives and it works great.

The thunderbolt version may not be an enclosure but it is a great way to get as fast of speeds as possible with single drives and would be great for SSD drives.

Seagate GoFlex Thunderbolt Adapter STAE121 B&H Photo Video

desktop version does have two thunderbolt ports.

Brett Sherman

Did you get the enclosure?

I see there is an option to have dual TBolt ports for daisy chain

Check this out:
OWC's Elite Pro External Hard Drive + Lacie's Thunderbolt eSATA Adapter Combo Package - Up to 8.0TB Storage (http://eshop.macsales.com/shop/Thunderbolt/Elite_eSATA)

I pulled the plug, get one of this eBOX-TeSU from AMAZON, base on AMAZON user's reviews
It's solid, easy - set up a RAID take less than 2 min.
I have to say, it's a good purchased

I currently have a G-Tech 4TB Thunderbolt RAID.

I would love to switch it out for a replaceable drive unit though... it's true that they're a complete rip off... although performance has been superb - it's a noisy and sometimes poorly reviewed item, which doesn't fulfil me with confidence moving forward as it ages.