Sam,
I got the tubing at Sportco. I bet OE carries it as well.
It is 1/16 diameter.


I inserted a small piece of 1/16 diameter hard tubing into each end. That allows me to add a junction tube to the tail and burn the front tube to keep the bead or cone in place like what you would on a Shock & Awe.
Here is what it looks like before tying it with the junction tubing added as an example.


SF