When you do not use flint to make sparks you rarely if ever get fire from another type of material if it is made of metal. The hardest metal is Tungsten steel used in manufacturing and you can grind it with any kind of grinding tool and it would last forever. But, here's the best part. You can stand (fully clothed) in the direct path of any kind of steel being ground down with a spinning grinding disk and it gives off 5 to 7 feet of sparks. It is extremely bright to watch even in the brightest light but, it contains no heat. Yes, believe it or not you can put a cotton shirt up to the sparks and even tickle your bare hands with the sparks because they are not actually on fire. They are micro fine bits of metal and I stand in them all the time at work.
If we add a battery charged pack to a small grinding wheel and put a spring loaded piece of Tungsten steel next to it, you then can put off tons of cool, safe, sparks for years. The toy would be hand held and small. It won't start fires and it doesn't do any damage to clothes. The only thing you get is tiny little specs of burnt up metal but, the metal is just a small piece of burnt up nothing. It's not sharp at all it is just dust. Steel dust. We may need an age group but, besides having a personal laser, this toy is a must have for us grown-ups.