Here's my latest: a two-layer (or two one-layer) top quilt using two Costco down throws. It's based on an idea I got from blide, here: https://www.hammockforums.net/forum/...hrow-Top-Quilt. Shout out, and credit where due.

modular two-layer cdt tq.jpg

I started with two full size CDTs, the horizontal seams ripped to increase loft. I folded each one in half on the longest diagonal, then turned up the bottom corner and stitched a triangular footbox, taking care to make the two quilts mirror images of one another. (This will minimize cold spots, I hope). I stitched all the way up the short side on each quilt, making two asym TQs. I made the footbox on one (on the right) slightly narrower than the other. That one goes inside. . . .
2 quilts.jpg

Then I turned the outside quilt inside out, lined up the footboxes, and set kam snaps at the corners. The outside quilt is on the left.
snapped together at foot end.jpg

After some experimentation, I added just two more points of attachment. One's at the midpoint of the leg-and-foot box (two short bits of mason line pulled through the fabric (of each quilt) and tied together with a square knot). The other is at the center of the head end, in the apex of the triangular gap between the two layers. (For now, it's hand stitched together. I'll go back and replace the stitching--with mason line, probably, since I don't want the bulk of a kam snap right there in the hollow of my throat).
4 points of attachment.jpg

I'm hoping that these four attachment points will suffice. I want to minimize the compression of the down, on the one hand, and to maximize the ease with which the two modules can be separated in the event that I ever find myself wanting less insulation on top. . . .