My latest project is a torso or 3/4 length down underquilt. I haven't filled it with down yet, but have finished all the steps up to adding the down, sewing the end shut and adding the suspension.
I started with the usual 1.1 ripstop seconds from D.I.Y. Gear Supply and using MADD777's calculator (underquilt section of the spreadsheet) from the DIY Burro Top Quilt calculator.
A lot of this has been done throughout the forum so I'll just post the pictures and leave a link to the .pdf on my Google Drive. There will also be a link to the original .rtf file also - the .rtf weighs in at 55 megs due to the number and size of the images. The .pdf is only 2.6 megs in size and looks like crap after the conversion I used. The pictures are large and show alot of detail.
The final dimensions are nine 3" baffles and is 56 inches long and 46 inches wide. For a 20% overstuff it will take 1.33 oz of 850 fill down in each chamber for a total of 12 oz. This is calculated for 0 to 20* depending on how warm you sleep.
Sorry - my scale is on the fritz so I don't know the exact weight. I'll post the correct weight after I fix the scale. I believe it's around 8 oz or so.
I used sewn channels to save weight.
Public Link to the PDF - https://docs.google.com/open?id=0B9I...VhmRXNLRkJhSnM
Public link to the RTF - https://docs.google.com/open?id=0B9I...3BZS3FuRFNlRjg
On to the pictures!