How can I create a USB RAID?

Reading this link, it describes how to make a RAID array out of USB sticks, however it describes the process using Gentoo now I don't know about gentoo and have never used it, but I'm supposing this is possible in Ubuntu if so how?.

Ubuntu uses udev so you don't need to execute the mknod command in those instructions.

As mentioned, mdadm is well documented as doesn't care whether the devices are hard disks, usb drives, or even LVM partitions. Examples:

Create a mirrored partition:

mdadm /dev/md0 --create --level=1 -n 2 /dev/sdb1 /dev/sdc1

4 disk RAID 5:

mdadm /dev/md5 --create --level=5 -n 4 /dev/sdb2 /dev/sdc2 /dev/sdd2 /dev/sde2

The guide that you linked will be the same with ubuntu. The raid utility "mdadm" is fairly common and well documented.

You will need to apt-get install mdadm to have this tool available.