Go to hardware store & get small diameter pipe insulation. You can cut small lengths w/scissors & slip over cable where touching. Doesn't add any weight. I use a combination of misc. pieces of foam to separate cables.
To keep cables off the floor, I use small terra cotta pots w/a piece of self adhesive foam on top.
To keep cables off the floor, I use small terra cotta pots w/a piece of self adhesive foam on top.