Drilling a hole in a glass bottle?

[Nightcrewman]

The bit that Dremel markets as 'tile and masonry' which is a sharply-knurled carbide rod is ideal for drilling glass. The 'glass' bits are more for engraving.
You must fill the bottle with water and sink it up to the level of the hole in another bucket of water as you drill, to do 3 things: Cool the glass (cracking), cool the bit (dulling), and damping the vibrations (cracking). Use a plug-in type dremel tool as the battery ones don't get up enough speed to do the job fast.

Spot on, filling with wet sand is good to dampen vibrations as well, it's sometimes easier than working in water, another good tip is to put a bit of tape, most kinds will suffice, onto where you are drilling this will stop the drill bit sliding or skiting about the glass when you start drilling. This is a good tip for drilling tiles or any smooth ceramics not just glass.
Remember safety glasses, you have only one pair of eyes.
Have fun.

NCM