The glass cutter is Husky brand from Home Depot, about $2. Put a small amount of oil on the cutting wheel before starting. You can cut it dry but the oil makes the wheel last longer.

-Rotate the bottle in either direction applying slight downward pressure to the bottle so there is a clear line with no gaps all the way around the bottle. The line doesn't have to be deep.

-Next light a candle and hold the line on the bottle just above the flame and rotate until it's warm. Then, dip the bottle in a bucket or large cup of water up to the line.

-Repeat that until the bottle separates into 2 pieces, It will probably take several tries.

-You can use ice water to speed up the process, but there is a much higher chance the bottle will crack going up or down the side instead of along the line.

-After the bottle separates use wet sandpaper starting at 60-100 grit to smooth any jagged or sharp edges on the inside and outside of the rim.

-Once you knock down the high spots smooth it even further with 200-220 for a comfortable surface.

-Wash the glass thoroughly before using.

NOTE: I did use a rotary tool with a coarse drum sanding attachment to lightly hit some bad high spots, but if you do this WEAR EYE PROTECTION AND A FACEMASK / RESPIRATOR. Also use gloves and keep the rim of the glass moist to prevent glass dust getting into the air. You don't want to breathe that stuff or get it in your eyes.