[ToddF]

One legal way to provide some measure of protection of your tanks from external damage, or shrapnel containment would be to use expandable mesh sleeving. This is the stuff usually used for wire bundling, and which also can be used to make pneumatic muscles.

McMaster Carr has it in various colors in a size suitable for slipping your tank inside.
ID range: 1 1/2" to 3 1/2"
Part number: 9284K419
Price: $14.53 for 10 feet.