They were plastic by the time I existed, but I had one with Ninja Turtles on it.
Discussion
The metal ones made the best sound when you banged on them after they were empty. I’d keep mine until they were all dented and falling apart. Everything just rolled around inside so by lunchtime my sandwich looked like it has been dropped off a cliff and stomped on by an elephant.
Can’t recall what was on my metal one.. but it was replaced by ALF. sadly ALF was plastic.
We were poor. I had one of these 
You weren’t really poor unless your lunch bags had the name of the budget supermarket printed on them.

