There's a new kind of extruded plastic, two-liter, soft drink bottle on the market that can be turned into a great little soda bottle terrarium in a matter of minutes. And you don't even have to like what's inside the bottle, much less drink it, to make one of these miniature greenhouses. In fact, you'll do yourself and the world a favor if you scrounge roadsides, or public "dumpsters" for your supply of empties.
When you have one of these throwaways in hand, just pop off the black plastic bottom section. (This requires a bit of force, but it will come off if you squeeze the clear top enough to get a firm grip on the outer layer of plastic.) Then, behold! The base of the bottle is an instant flowerpot—it even has three holes in it for drainage.
Now, with a sharp or serrated knife slice the clear part of the bottle across its diameter just at the point before it begins to taper. There's a small bulge here that you should be able to feel. When you divide the container immediately below that, you have a plastic dome!
The next step is to cut a small slit about two inches long on one side of the dome. Then, overlap (very slightly) the two edges of the cut, insert the open end of the dome into the pot, and you'll wind up with a very efficient terrarium, miniature hothouse, seed-starting bed, or sprouter (to grow edible sprouts, put wet paper towels in the bottom instead of dirt).
If you want to, you can leave the label on to provide a sunshade for tender seedlings, then rip it off later. The label (or any remnant thereof) also makes a handy place to jot down the dome's contents.
In fact, nothing need be wasted in this operation. Even the leftover neck of the container can be used as a funnel or as a "hot-cap" for delicate garden plants.
All in all, bottle recycling is almost enough to drive you to drink—soft drinks, anyway!