Fire with sparks from the spine of the Laser Strike from @ and a piece of quartz. There is a big difference between using a dedicated hardened striker and a tool that you happen to be carrying. For me, the real value in practicing flint and steel (percussion fire) is in the fact that the tools we are already carrying can serve double-duty as emergency sources of ignition.
However, this isn’t quite as simple as it may sound. Of course you need charred or otherwise suitable material to take a flint and steel spark in the first place, but this can be accomplished by making your first fire by friction and using that fire to make char; which should make the next fire easier.
Flint and steel is easy with a dedicated striker, sharp piece of chert, char cloth, and a hardened striker. Swap any of those out and it gets more difficult. Tools usually aren’t as hard and don’t throw the same volume or intensity of sparks. Quartz doesn’t hold an edge like flint or chert, and natural char can’t always be held on the stone. This can turn an easy task into an advanced exercise in frustration.
There is nothing wrong with carrying and using a dedicated striker though. For practice or enjoyment, it is safer, more effective, and saves wear and tear on your tools. A steel striker in an emergency kit would probably be better replaced with a backup ferro rod, but as a training tool it is excellent. For those of you that don’t know, a piece of an old file will work as well as most commercially produced strikers, so that can be a great place to start.
Folding saws and knives are the safest way to start when you want to begin practicing with real world objects because you can often use them closed. Using a fixed blade knife is much more dangerous and extreme care must be taken. There are multiple ways to get sparks from a knife, including swinging the knife, but you have to be careful no matter which method you practice.