Currently Being ModeratedDec 13, 2012 2:29 AM (in response to Nigel-66)
AFAIK there are no USB drives that can be daisy-chained, so you'll need to use two USB ports of your Mac, or an external USB hub.
However, with Disk Utility you can do a software RAID 1, so setting up two separate drives for RAID 1 is possible.
Currently Being ModeratedDec 4, 2013 6:56 AM (in response to Nigel-66)
This should answer your question: http://pietrzyk.us/12tb-raid-0-under-400/
There are step by step instructions for RAID 0 here: http://pietrzyk.us/creating-a-striped-raid-set-using-mac-os-x-disk-utility/
and RAID 10 here: http://pietrzyk.us/raid-10-using-mac-disk-utility/