Just got through making a top bag that has a slit down the middle of the single layer of bottom fabric, (acts more as a quilt). It took just over 5 hours while watching the SF Giants double header games last night. For how light this is, it is toasty warm. Did a perfect job at just making it wide enough to not have any drafts as well.
Used Momentum 50 with 5.4 ounces of 900 fill. The fabric weight before stuffing was 4.4 ounces, total weight 9.8 ounces. Loft is just under 2 1/2"
The top was just made to fit my body. I even did some extra sewing lines to make it fit better around both the feet and the shoulders. The top with down is 38" wide at is widest. There is a 6" filled collar that goes under the head that the bottom single layer is also sewn to.
I stitching is a 14-8 Karo style with sewn through stitching.
This was made to add a good degree of warmth to a bag as well as serve as a it's going to be a warm one quilt.