I would like help on copying an EXISTING Lion partition, with a couple of key apps on it, to a thumb drive that is bootable. The size of this partition is about 7 Gigs. Thus, I want a thumb drive back-up of my Lion OSX that I can boot in case of an emergency. Am using a Mac pro 2,1. Here is what I have tried so far: 1) Have succeeded in creating bootable copies of my current Lion OSX partition, and my old Sno Leo partition on an INTERNAL third hard drive just fine. 2) Have booted into an old Sno Leo partition, and used disk utility to "restore" my current Lion 10.7.4 installation to a partition on my PNY 32 Gig USB thumb drive using GUID. Disk Utility Info shows that this thumb drive as bootable 3) However, when I hold down option at boot, with thumb drive in front USB port, the thumb drive is never displayed; at boot, OSX will not recognize thumb drive as a bootable option! Five other bootable options are recognized, and all are bootable: Main Lion, Lion BKUP, Main Sno Leo, Sno Leo BKUP, and Recovery Disk. Why isn't my thumb drive displayed as a bootable choice? 4) I took out all my drives, and just tried to boot with the thumb drive alone in place; it still did not display as a bootable choice. 5) I "blessed" the thumb drive in terminal with the following command: sudo bless -folder "/Volumes/USB Flash Lion 10.7.4/System/Library/CoreServices" It asked for password, seemed to work, but no cigar: no listing of thumb drive as a bootable volume when holding down option key. Solution Paths Please suggest a solution path, if it is possible. It could be that Lion, or Apple, FORBIDS making a bootable copy of an existing, bootable Lion partition on an EXTERNAL USB drive. If so, please point this out to me. Here are some ideas: 1) I could buy from Amazon an external terabyte drive with firewire for $190. Then, I think I could copy my existing Lion partition to this external firewire drive, and have it bootable. If a Colorado wildfire takes down my home, I could quickly grab this drive and put it in my car. But this is an expensive option; a 32 gig PNY thumb drive is only $20 at Best Buy. 2) Do I need to "bless" my thumb drive in Mac Unix to make it bootable? Did I make an error in my sudo bless command described above? 3) I have already clicked "repair disk" in disk utility from my Sno Leo partion, and it reports that it placed a boot on the thumb drive, and that the Lion thumb drive copy is clean, and bootable. But I cannot figure out why it is not recognized as a bootable OSX at startup. Thank you for your patience and any ideas I could try.