An easy way to sharpen flints

An easy way to sharpen flints is to use a Dremel tool and a wheel called a "Mizzy Wheel", or a diamond cutter used on the Dremel works even better.  You can sharpen a flint's edge till it's like a razor if you wish, or you can also flatten out the top or reshape the bevel as needed.  Just be sure to wear a mask so you don't breath flint dust.