Glad you asked this. It reminded me I had loaned my home made tool out about 3 years ago and not gotten it back. I was going to take a picture for you. Sorry. What I did was to make a 180 degree sleeve that would slip over the side of the spring. I welded heavy washers in the ends. I then could stretch the spring out with my vice, slip the sleeve over the spring and that would keep it stretched until I installed it on the car. When I lowerd the hood a little it took the tension off the spring and I could remove the tool.
John L