There is quite a lot of methods to make a bottle neck guitar slide. Some using a rope blow torch and a hammer. Knowing me Id probably end up hurting myself or burning the house down.
Saw this video on Youtube
In short you need
Wine Bottle
Wine Bottle Cutter
Hot and Cold Water
Sounds pretty safe.
Score the bottle with your cutter. Heat up with hot water run under cold tap. Repeat that and the score line should crack leaving you with a smooth cut needing sanding.
Im going to try this tomorrow.
Ive tried using 2 beer bottles and a wine bottle.
Glass Cutter for £2.99 to score beer bottles then just used hot water and then cold water.
Needed a pipe cutter for the wine bottle which was a lot thicker.