I just ordered 5 yards of this lightweight Spinntex fabric to make a down TQ. Since it doesn't breathe, I'll need to add a panel to allow air to get into the baffles. I am going to make this in the Karo Box method. With 2" baffles, I am targeting a weight of <20 ounces. Now to start working on a design....

Here's my inspiration: http://www.suluk46.com/RandD%20-%20RD4%20WLQ.html