a little fine sand and a piece of pipe to bend the loop around
Have also had success using ice as well. Smaller pieces can go in the freezer. Larger projects need to wait for winter and go outside (at least for those of us living in colder climates).
I suppose you could try cooling using some liquid with a low boiling point, too, if available. Some sources suggest mixing the water with soap. I have only used just plain water.
For 360 degree bends, like a vibration loop, this method might work better anyways as some tube benders don't lend themselves well to making bends much beyond 180 degrees.
One other consideration if you go the hose method is the hose interface. Do you have a way to form a bead in the tubing where the hose slips over the end of the tube? This helps keep the hose from being pulled off once the clamp is installed. I know this is probably not a line that will see much pressure, but it is still good practice.
Finally, in the spirit of "any-job-worth-doing-is-worth-over-doing", you could also silver braze an AN fitting on the end of the tube, then use a piece of braided line with screw on fittings. If visible, it would look pretty cool, too.
The fittings are available in different sizes, and are counterbored to accept the tubing. 5/16" is difficult to find sometimes, so you can just use a -4 tube to -6 adapter, and bore the -4 side it out to 5/16". I have used this method a lot for oil pressure and fuel lines - especially if they are stainless steel.
Best Regards...
