In January 2025 I heard from Marcin. He'd been inspired by entries on the web site of what others had done with their thin clients:
Thanks to your website, I've successfully connected six SSDs to my old Futro S720 :)
The SSD's are 256GB capacity configured as a RAID 5 array giving me about 1TB of storage. This is running under Ubuntu. However Ubuntu does not support booting from a software RAID setup so my boot partition is on a separate USB drive.
Having checked he could connect six SSDs his starting point was to design and 3D print a small chassis to carry the six SSDs. This fitted in the free space within the S720's case.
As to connecting up the six SSDs he:
He also added a small fan to assist with cooling the SSDs.
Putting it together
In the photo above you can see (bottom left of the heatsink) the SATA lead emerging from under the heatsink and also the mSATA to SATA adapter. To the left of the heatsink is the mPCIe board carrying the other four SATA connectors.
All the wiring in place.
The finished item consumes ~9W when idle.
The setup has been up and running without any issues for the last year.
I would note that whilst Marcin has had no issues with powering his array of SSDs from the +5V line on the internal USB port YMMV. Whilst the USB 2.0 spec says '+5V @ 0.5A' many/most USB ports provide 1A or more. The D3313-F spec does mention: Onboard Power Output (+5 V / 2 A, +12 V / 2 A) for drives so the capability of supplying at least +5V @ 2A must be there.
If you do have power issues with your particular choice of SSDs my fall back would be to add a small cheap 'buck convertor' powered directly from the +19V supply input.
The SSD chassis: https://www.printables.com/model/1163353-six-ssd-bracket