Addison I probably could get it down to 5 oz just by using the lighter blue material and a shoe string instead of paracord 550. Down would be nice also, but I don't know if it would hold it's shape for the side sleep mode once you put the weight of your head on it, I think it would compress to much, who knows though it might be fine.
I started with the material inside out and sewed a hem about 1/4 inch from the edge then I trimed that down to 1/8 inch, sew almost all the way around to the middle of what I would call the top, I left about 1 inch open so I could turn it inside out again.
I then inserted the paracord, enough to go all the way around, then starting at the opening I sewed another hem about 3/4 of an inch from the outside, leaving the cord against the outside edge, if you go smaller than 3/4 it will be to hard to draw the cord tight, trust me I did it smaller and had to go back and rip out all the stitches, keep sewing all the way around untill you get back to the opening and leave the same amount open as the first opening.
Then I took some poly fill and shoved it in the tiny hole, which worked, but left me with small little clumps of poly instead of one nice big piece, it's fine but if I had to do it again I would do it like Grand Trunk did it, by cutting the material all the way across fromm side to side, and then stuffing the poly in, and then sewing the opening back up with a seger to give it a nice edge.
After I filled it to what I thought was a good amount I sewed the inside hem all the way, and then sewed next to the paracord so it wouldn't rip when I pulled on it.
I'll try to post some pics of the opening later today