Use an old file. Grind off one surface with a good grinder. Then, using an acetylene torch- a propane torch can't get the steel hot enough, in my experience--- bend the end into a hook, with the smooth side OUT. The smooth side is the face side that you strike with your flint.
Now, you have a choice of leaving the other end "straight", or also bending it, so that the striker takes on the shape of the letter " C " . Strikers come in different shapes. "C", Upside down "J", Round, Oval, even with both ends closed on the middle of the long arm, to form the letter "B".
An old file should have enough carbon in it, that you don't need to harden it to get sparks. If it doesn't spark well, heat the striker up and dump it into quenching oil- vegetable oil that is warmed will usually prevent the steel from cracking.
Expect the steel to light the oil on fire, so do this away from flammables. Have a garbage can lid, or some other lid to snuff out the fire.
If you close both ends of the striker, you want it long enough to comfortably let your full hand into the "C" or oval, so you can hold and control the striker when you strike it with a chunk of flint to make sparks. :thumbsup: