easy tubing bending Q

If you buy the copper nickel stuff that all the rage at the parts stores, or even the steel tubing we all know and hate. I found if you load the tube with a piece of steel cable that fits right and tight, and grease the hell out of it- it will bend rather tight and not collapse. After like 2 bends you will not want to bend any more because the steel cable will get caught in there and only an act of GOD will get it out.

Some info on line suggest using sand and capping the ends then bend. My only issues is how do you know it’s all out.
Transmissions, sand and me don’t get along.
Syleng1