Do toilet paper rolls collect at your house like they do at mine? I happened to have the collection below on hand from what I was saving for kids' projects, allowing me to do this endeavor on a whim. Here I have marked them each with dashes at 1" intervals. You will want to decide how "3-D" you want your wall hanging to be. Mine is going in a small space and so I chose to make only a 1" protusion from the wall.
Cut strips where you have markings, it is actually perfect if the roll bends and creases as your scissors squeeze it together. Hot glue the rings together in whatever fashion you dream up.
Take it into the open air and spray paint that baby. I used a black gloss because that's what I had.