Hey everybody! Just thought I'd post some pics of my DIY underquilt. Made this based on Shevy77's design. I ended up with a few more inches than him on the differential and also about an inch less on the baffles due to sloppy measurement. I also had a much longer un-darted section in the middle. The results were good though, I think. I used 1.5oz/yd calendared ripstop from BWDD for the shell, some nylon mesh from Jo-Anns for the baffles and salvaged sleeping bag down for the fill.
The only thing I wish I'd done differently would be to measure and mark darts for the long side to account for the differential cut in that direction... As it was I had to just do it by eye, which turned out a bit irregular. An 'easing' stitch would probably work too. The short sides were easy to do by eye because I could just pin each side together where the baffles were stitched and fold over a bit of the longer side in the middle to take up the slack.
I stuffed the hell out of this thing, so the total loft ends up being about 5 1/2 inches. Laying on it at 38 degrees F feels like laying on a sun-warmed rock--but fluffier. Anyway, you get the idea; it's toasty.
The attachment is 1/8" shock cord terminated with mitten hooks, hooked to mason line loops which are tied to my Amsteel Blue ridgeline with Kleimheist knots.