After determining the proper needle size, I hold the needle and spin the shim stock around it, then finish with sandpaper. Look at it under a strong loupe and back lit to verify no burs and roundness. With the correct size, it will be very sharp. I have never tried it, but have heard of people using arcing electricity to burn a pinhole in to the shim stock. Not sure how you would control the size, but it sounded interesting.