After trying to decided whether or not I should buy a Nunatak BCB I finally went with no and bought a sewing machine instead.
After a couple weekends of work (due to waiting for down delivery) I now have an underquilt for my TTTM hammock based upon the size and dimensions of Te-wa's design.
I decided to go with a sewn through construction for my 1st sewing attempt just to keep things simple.
http://is.pinkbike.com/photo/4267/pbpic4267764.jpg
http://is.pinkbike.com/photo/4267/pbpic4267755.jpg
http://is.pinkbike.com/photo/4267/pbpic4267748.jpg
http://is.pinkbike.com/photo/4267/pbpic4267730.jpg
The outer is Ripstop pertex in a charcoal grey and the inner a teal pertex microlight. Both around £3 per metre. The fill is 180g of 800 (EU fill) polish down.
I have some red and black pertex quantum along with some no-seeum netting ready for the main event - the unsponsored back country blanket.