My cousin drove to a Utah Lake beach in Dec. Put a hose in the tail pipe, put the other end inside a window and rolled them up. It was his mental state that drove him to do that. It wasn't the car. It wasn't the hose. It was him.
I could leave a loaded and cocked gun on my kitchen table and if no one ever touched it, it would never fire the round. (Ok, maybe in thousands of years if my house disintegrated around it and the wind and rain eventually rusted the mechanisms it might.)
The gun is a tool. They make suicide so tragic because they nearly guarantee a successful attempt.
A gun doesn't take the life of a suicide victim. The individual who decides to take their life did that. They see no way out of their problems, so they choose to end those problems. A gun in almost all cases prevents a failed attempt.