I'm at my ancestral estate for the holidays. One of the stranger things I found in my storage unit -- strange in that I had forgotten I had them, not that they're any stranger than any of the other stuff I found in there -- were two empty bottles of Wegmans brand balsamic vinegar. Why did I save these things? Uh … oh, that's right, because I lost my glass guitar slides in a flood a few years ago and still haven't made these bottles into their replacements.
Don't let the pricks at Guitar Center fool you -- the best metal slides for playing slide guitar are sold at Sears for six bucks. Glass slides are a little trickier -- Coricidin aspirin bottles [whose production was discontinued decades ago] are considered the gold standard, but I prefer to make my own. It's fun, cheap, allows you to choose the color, shape and thickness of your slide … and it involves igniting kerosene and then playing with the object you just lit on fire. What's not to like?
Now, you really, really … really shouldn't do this; it's dangerous. But, here's how I used to do it:
1. Find a bottle that comfortably fits my left ring finger; I had a full-finger slide and a knuckle one for being able to play chords and slide at the same time. I don't think I ever used the knuckle one after the first week of having it, as 1. I am not, nor shall I ever be, Muddy Waters, and 2. knuckle slide is far more effective as comfort -- knowing that you have it as an option -- than whatever benefit you would gain if it was ever actually deployed; it's like the U.S. Navy's nuclear submarine fleet in your guitar case.
2. Clean and dry it out.
3. Secure an exacto knife on a stack of books set to the height of the bottle where I want the slide cut off, with a smidge extra for sanding.
4. Turn the bottle to score it nice and even.
5. Wrap a piece of string around the score line, add about an inch extra.
6. Soak string in kerosene.
7. Tie string securely around the score line [go wash the flammable liquid off your hands] and LIGHT ON FIRE FOR FUCKSAKE BE CAREFUL MILO.
8. Wearing gloves, hold the base of the bottle. Rotate it slowly and let the string burn until it goes out. [BTW, I hope we're outside; I'm trying to recall if we ever tried simply rolling the bottle on the driveway rather than hold it.]
9. Probably repeat step 6-8; wine and vinegar bottles are thick.
10. Once the burn line is pretty eaten away but the glass is still looking/smelling hot, take the slide end of the bottle and either bonk the base against something flat but forgiving [CAREFULLY] or dunk it into a bucket of cold water [DELIBERATELY].
11. File and then buff the jagged edge of the bottleneck until you can't hurt anything but your ears with it.