Although this technique is hardly going to revolutionize the recycling industry, it is a cool way to turn a common trash item into an object of beauty. Before a light bulb can be used as a container, the end has to be opened and the "guts" removed. This article explains how to do just that.
NOTE: Any operation with glass, including that described in this article, is potentially hazardous, and should not be undertaken without adequate safety gear, which should include ANSI-approved safety goggles and gloves, among other things.
The first thing you will need, obviously, is a light bulb. The ecologically correct thing to do is to use a burned-out bulb, but the world probably will not end if you buy a new bulb just for the purpose. Use a clear bulb, rather than a frosted one (as illustrated above), because the material sprayed inside a frosted bulb is easily scratched, difficult to remove, and may not be safe to expose yourself to. Some light bulbs are manufactured in a rectinlinear "faceted" shape, which will stand upright unaided. The common "round" style bulb, however, will need a rubber O-ring (see photos below) to stand upright on a flat surface.
Work over a trash can, empty box, or outdoors where the tiny bits of glass and other debris this process generates will not be a nuisance to clean up. Begin by removing the flat brass terminal on the socket end of the light bulb. First, squeeze across the diameter of the terminal with a pair of needle-nose pliers, so that one of its edges curls up. Next, grab the curled up edge of the terminal with the tip of the pliars, and pull straight out along the axis of the bulb. The terminal should pop out neatly, leaving only the shiny black silicate insulator material, which may be removed by inserting one jaw of the needle-nose pliars into the hole left by the terminal and gently twisting and prying to break it out, chunk at a time.
Once the dark glassy insulator is gone, you'll be left with an open metal threaded socket. Looking down into it, you'll see a glass tube descending into the interior of the bulb. Inside that tube is an even smaller tube, about 4mm across, that points back up toward the opening. Squeeze and shatter it with the tips of the needle-nose pliers. You will hear a whoosh as the vacuum inside the bulb breaks. Now take a rat-tail file, insert it into the space where the small tube was, and gently pop it against the bottom of the larger tube until it breaks out. Once you've got a big enough opening into the bulb's interior volume, insert the rat tail file and gently work the teeth against the edge of the broken hole. This will cause the remaining glass to chip out bit by bit. Continue enlarging the hole until it is as wide as the adhesive on the inside of the threaded base permits.
Frosting on the inside of incandescent bulbs can usually be removed simply by washing them out with water.
It probably didn't start with this; it probably started with somebody, somewhere, taking an old light bulb and turning it into a salt-shaker, essentially as described on this page. Then somebody else, with a head for marketing, came upon the idea and thought, "That's clever. People would buy those," but when confronted with the manufacturing and distribution difficulties associated with making salt shakers from real burned-out light bulbs (Are they food safe? Where do we buy burned-out bulbs in bulk? Will they seem too cheap and fragile for anyone to actually spend money on?) decided to just make a salt shaker in the form of a light bulb. They did so, and I saw one in a catalog somewhere, and instead of thinking "Gee, I'd like to buy some of those," thought, "Gee, I'd like to make some of those from real light bulbs." Which I did, and here they are:
The discovery that plastic caps from 16 oz. soda bottles fit the threads of a standard light bulb was exciting to me (feel pity), but apparently I'm not the only one who's made it. That, or somebody saw the idea on my page before he/she made these...
...which won the ReadyMade Magazine MacGuyver Recycle Challenge for issue #8 over my box of light-bulb Xmas tree ornaments. But I'm not bitter. (They even say so in the copy! "We received more than a few bright ideas for our latest challenge. Tree ornaments and vases topped the list...") But I'm not bitter. (I was even thinking: "Salt shakers. That's so cliche. I bet everybody sends them salt shakers. Xmas ornaments will be more original.") But I'm not bitter. (The idea was posted on this page years, years before ReadyMade even existed.) But I'm not bitter.
Ahem. Excuse me.
At any rate, the big weakness with this design is that the light bulbs won't stand up under their own power. You need to add o-rings (my solution) or heavy weights inside the bulbs (Hetal Jariwala's admittedly-superior solution, using machine nuts cast in candle wax) to keep them from tipping over on your table, unless you use "specialized" bulbs which are more amenable to standing on their heads, like the 30W indoor floods I used to make these:
These 30W bulbs are commonly used in track lighting. Most have a metallized coating applied to the interior. This can be removed by pouring pool acid into the bulb and letting it sit for an hour or two. After this treatment, the bulbs are thoroughly rinsed with water and are completely safe to use. Obviously, no one who is not familiar with the safe handling of strong acids should attempt this. There are other species of bulbs, notably some of the newer "halogen" varieties, that also have shapes which would stand up better than the traditional bulb. These, of course, are much less likly to be available as refuse items.