when i did mine i cut the glass just above the screw. after i filled the neck with sea i tied a monkie's fist at the cut. thats when the neck of the bottle started to crack. that is why i had to keep the monkie's fist going up the neck. after, i screwed the the bulb in to the female part and fastened it to the base.
john z's way sounds like a good way.
yes but its not nessesery. i have three of them small, medium, large.
some times, depending on the bottle the ends will be bent wider than the part you hold.
thismeans you need to close the inside ends carefull as not to change the messurement.