This terrarium we will be making will be only one part. However, you may also do the water part if you want.
You may use this terrarium for planting or for making a habitat. Whatever you do, it is still a cool way to bring the outdoors in.
Step 1: Materials
To start out, you will either use one or two plastic bottles. In reality, you can actually use as many as you want, but the way you connect them will vary.
Step 2: Preparing the Bottle
After you have your two bottles, you will want to take the paper or plastic covers off. This way, it will let in more light if you are putting plants in it.
Step 3: Filling
After stripping the cover off the bottles, grab one and fill it with dirt for your critters or plants.
Step 4: Oxegenate
To provide your organisms with carbon dioxide or oxygen, you must allow them air. Poke holes in the sides above the dirt to ensure that not all the water evaporates, but still keep quite a bit inside the bottle.
Step 5: Completion
Now you have completed your terrarium. Now, you can also fit in the optional step; adding in the top layer. This top layer can be the water habitat. Fill the bottle with stones and dirt and other things to prevent large leaks. then, put a mesh net on the bottom to catch the stones and you are done with your habitat!
By the way, I am entering this in the reuse and unusual uses for ordinary things contest. Please vote for my instructable if you like it!