I happen to stumble upon some YouTube videos about using USB Flash drives to build a RAID.
One quy was using a Raspberry PI with a couple of USB Flash drives, to create a RAID hard drive storage system.
https://www.youtube.com/watch?v=CCISPm9KekY
There is a Link on the above YouTube video to the guys other video, about how to set up the NAS software on the RPi. This is a very excellent video!
https://www.youtube.com/watch?v=DPGpMSFZc9A
Another guy used a 10 port USB Hub to mount 8 USB Flash Drives and create a RAID hard drive storage system. I believe he was using the Apple OS.
https://www.youtube.com/watch?v=CCISPm9KekY
I am sorry I missed Bob's presentation on the RAID hard drive storage system, but the above might be an interesting project to look into.
Bill
I saw a different video of a guy setting up a RAID array using flash drives some time ago too, and had mentioned it to Bob. It's definitely a very geeky thing to do though I wouldn't depend on the data on it (but it might be good for a secondary backup). Also probably a good way to learn RAID without having to require the extra expense of a bunch of hard drives since many of us already have a bunch of flash drives lying around. Thanks for the share, Bill!