It's very unlikely that I'm the first to think of this but I can't seem to find anyone else having done this before. Have given up on wading through all the top and under quilt projects on here...Anyway, this is the idea:
I want to make a multi-purpose down quilt. I'm thinking 60"x70" to provide a size that I can use as for camping with my better half (she doesn't camp in cold weather so this would be enough warmth. The quilt would have two footboxes.
I would then like to re-purpose this as a sleeping bag by attaching the sides (likely with a zipper) and the bottom with shock cord. When you get into the bag, I would then just need to put my feet in one foot box, and then the other to close off the bottom. I'm thinking that if this doesn't stay put well over the night then I can look into velcro or magnet solutions to help secure the foot boxes together.
Finally, it would serve as a "complete quilt" for hammock camping with the shock-corded bottom and having half of the head edge with shock cord. To pull the edge up to the hammock there would be a cordlock at the edge and the shock cord could be secured, inside the sleeve, at the middle of the head edge. (probably just do both sides)
I don't really foresee any problems with the quilt and sleeping bag but I can imagine there is going to be some difficulty getting the "sock quilt" idea to work. Either it makes a closed off tube and accumulates lots of condensation or there is a big hole near the head.
How I'm thinking I could solve this problem is to have the side edge attach to the hammock, curl underneath and then attach again to the other side (providing an under quilt with lots of extra quilt hanging free. The leftover quilt bit can be tucked and placed as needed around me. Essentially, have an under quilt that is twice as wide as needed and the extra width becomes the top quilt.
I know it's a bit of a read so I'm not expecting to get a lot of feedback and I very much appreciate what I do get.