Elizabeth, Use a fine (2 mm) diamond coated drill bit in a jeweler's
drill press. Make a dam for water around the hole with an oil based
clay. The Drill must be constantly cooled, by drilling through the
water. Work slow, go up and down regularly. You'll get a feel for
the cutting of the bit. Another more primitive, but equally doable
technique is to use the sharp corner of a file, with kerosene as a
lubricant, hand twist grind a hole into the glass. Do half from one
side and half from the other side. This technique will take a
little longer, but it is immensely satisfying. Or if you get a 1/8"
spear point glass drill bit, you can do the same thing quicker. And
you can use any kind of drill at a very slow speed. Again kerosene
is needed as a lubricant.