Making a glass guitar slide is quick and easy when you have a handy dandy mill file,
And some pizza, oh, beer too, You need that, or any glass bottle really.
Step 1: Supplies
You need a Mill File and a glass bottle, any will do, but with beer, it makes the time pass by quicker.
Also, You will need some food too, pizza is the best choice, goes good with making things.
You might want to put in a good movie or some awesome music as well.
Step 2: Start filing.
Remember, you are working with glass, which can be sharp! Don't cut yourself, Don't be reckless and do this all gloveless like pictured, he almost cut his finger on glass (But in his defense he didn't think it would work...)
Wear a mask too, will protect you from inhaling all those dangerous glass dust bits. :0D
Eye wear would be nice as well, No one wants glass in the eye.
Start off just filing away a bit at a time, gradually turning the bottle as you do so, keep going over the marks you are making, occasionally tap it on the edge of a hard surface, carefully so you don't shatter the glass, Keep this up for about 15 minutes or so, depending upon how much effort you are putting forth and it should just pop off the bottle.
Step 3: Finishing up
After you have gotten the neck off, you will want to smooth out the area where it was cut so you have no sharp edges.
Step 4: Extra step
If you want to go for a slightly more finished look, you can go a step further and file off the lip of the bottle, Mind you the glass is much thicker here so it will take much longer unless you are all fancy and have a dremel tool or a glass cutter, but if you have those, then why would you click on an instructable showing how to make one with simple tools?
Step 5: Finished!
Now go show off your ultra cool DIY glass slide to all your friends and play them some kickin' tunes.