I just punched my first pinhole and it was terribly exciting. Again, I'm using .002" brass shim stock glued to matte board carriers. I used the first part of a "Precision Point" pin, it's body measures .0271" in diameter, and as far as I can measure (with a loupe and fine ruler) the diameter of the hole is about .018-.020". I held the hole up to my eye in order to look through it which was pretty amazing. The pinhole effectively turned my eyeball into a camera (I know it is already) but it was still a bit different having an image projected into your eye, than having your pupil be the aperture.
I can't wait until the photopaper arrives.