Looks fairly simple to make one, I wonder what sort of rope they use.
I like Running Feather's rig. Couldn't you just put the scrunchies on the amsteel hammock rope? Small bungee loops might work, too, or even large rubber bands - anything to keep the sticks in place until the line is tightened. Wait a minute - there might be a problem with abrasion on the scrunchies if they were squeezed between the sticks and the tree or the amsteel. Maybe RF got it right the first time.
That is a very inventive strap alternative idea. FWIW I prefer these for now:
I haven't found them to stretch, probably because they are for ratchet straps and stretch in those is bad.
A 10' length of this stuff (one long strap from a set) weighs ~42 grams. I cut one of those in half and make two 4.5' straps. They are soft so there is no concern so far about sawing through from friction going through the eye (had that happen before on another material) and the are very tree friendly.