How to Make a Tiny Terrarium in a Light Bulb

As someone who's done shipbuilding in lightbulb glass, I need to add this:

DO: Wrap the bulb in a towel and hold it that way when you go to break the back end of the bulb off. I have a 3/4" scar between my right thumb and my wrist that says this is a good idea.

For such a "green"ish feeling that this project exudes, I am going to say that you should just wait for your existing bulbs to die and then use that instead. In fact, I wonder if bulbs could be recycled in this manner and spur a new business.

I wonder how a small cactus would do in a terrarium of this size? They shouldn't need much in the way of water.