Personally I like light, thin and bouncy tails, however...
To have a flexible and smooth tail.
1. Cut the tubing lengthwise into 4 pieces.
2. Tape the 4 pieces back together with the chain inside.
3. use a long doll needle and some button thread to sew threw
the tubing and chain links by inserting the needle and pulling
it threw and then move up and do it again.
4. Cut the tape so that each side can move freely.
This will create a loose web of strands to keep the chain in place while preventing it from bunching up.