I personally craft every bottleneck slide. Produced with wet tools and elbow grease. No heat has been applied to my bottlenecks. Throw the dull sounding Pyrex slide out and get the real thing. Tone to the Bone.
Most of the bottlenecks I offer in my store are made from wine bottles. Occasionally I will offer Grey Goose, Belvedere, Port, Grappa and Cognac bottles.
If you are just learning to play, Keni Lee Burgess is a great teacher and offers some really nice video lessons geared towards open tuning and resonators. These are very informative.