[Minyaliel]

I always use nails and sewing needles. Forks also give an interesting effect. Apart from that, I often use my fingers and then lightly stretch the fabric so that the threads will go from another but still stick together. That's an art, though, and needs practise. But really, to make those kind of holes you could potentially use anything that's pointy, sharp or has a rough texture as long as you've got the right technique.