There are typically so many experts on any forum I have ever beloged to that I hesitate to show anything I have, but I have used the setups in that attached pictures to work in trees and hang my hammocks for years.
Go to my album page and there are a few pictures of various sized webbing made into various pieces of equipment. I threw in the Big Shot just for fun. The first question I usually get asked is how I got a rope 150 feet into a tree from the ground.
My hammock hangers usually have sewn loops ever 24 or so inches so that I can make a knotless connection to my hammock with a carabiner.
Sorry that most of the photos are not seat belt webbing, but the white one comes closest at 1 3/4 inch. I generally buy tubular webbing in one inch for most of my stuff.
My interpretation of a tree saver is a unique piece of equipment that has a big ring and a small ring sewn onto a piece of flat webbing of about 24 to 48 inches, depending on what you are going to work from. It is deployed for work in a tree from the ground and retrieved from the ground. Tree huggers are used to swing a hammock or hold the bitter end of a climbing rope.
Thats my 2 cents
Took your post on straps made out seat belts and got 2 front seat belts nd cut the webbing out. They yield 2 straps 8 feet long each with loops on each end.straps are 1 3/4 inches wide. Hung my hammock up and filled it up with 300lbs dog and horse feed and left it there for a couple of days.one mistake is I hold have measured the height off the floor and length of the straps for stretch purposes..