Hi Bob, thanks for the comments.
http://www.purplelindacrafts.co.uk/prym-knitting-in-elastic-200m-invisible-elastic-thread-8896-p.asp is the stuff, I think Gold Zack is another brand name. WNW sell the same stuff for quite a bit more. It's also way cheaper than EZ line, in the UK we get 100ft for £12 whereas this is £2 for 200m. It is readily available in the UK from a multitude of places.
It's similar to EZ line but it is thicker and has a flatter profile so to that end it's more suited to the RFC style wires, but IMO in our scale it doesn't really matter.
The WNW builds on their site (not the customers builds) always seem to use this stuff for RFC planes.
If you are using brass sleeves it is harder to thread through the 0.3mm id tube due its width and flexibility. I found cutting it at an angle helps and when threading it through the tube for the 2nd time if you stretch a piece between your thumb and forefinger with the sleeve in the middle of the stretched bit this narrows the thread thats already in the tube making the gap bigger. Failing that a sharp knife will cut the thread in half length ways. I hope that makes sense, a picture would explain it much better.
As to size I'm not sure exactly put its not a precision product and like ez line can vary in width along its length. This is worth remembering actually because looking for a thinner width piece to thread through the tube may save you a lot of time against loosing a few cm's of thicker thread.
oh and I almost forgot you can paint it but I left mine as it came. I would recommend using extra thin CA to fix it as this stuff has the consistency of water and sets immediately.
