A terrarium is a miniature habitat perfect for housing small animals and plants. While some materials are more suitable than others, you can pretty much build a terrarium out of any container as long as it is enclosed on four sides. While not an ideal habitat, an igloo cooler can make a suitable terrarium. However, if used to house reptiles or other small animals, it must be cleaned frequently. The plastic that lines the igloo cooler is quite porous and perfect for breeding bacteria and other pathogens.
Clean the igloo cooler thoroughly. Use hot soap and water and a scrub brush to scrub the cooler. Then, rinse the cooler thoroughly.
Spread a 1 1/2-inch layer of gravel over the bottom of the igloo cooler. But first, clean it by dumping it into a bucket filled with 1 quart of warm water mixed with 1 tablespoon of bleach. Rub any dirt off the gravel with your hands. Rinse the gravel with water and dry it with a lint-free towel. Finally, spread the gravel over the bottom of the cooler.
Spread a thin layer of loose activated charcoal over the gravel.
Spread a 1-inch layer of sphagnum moss over the activated charcoal.
Spread enough potting soil to fill roughly 1/4 of the cooler.
Plant your plants. The type of plant that you use is largely up to you. However, they should be compact and slow-growing so that they do not overgrow the terrarium. Before you plant, consider sketching several possible plant arrangements.
Add rocks, branches, moss or other accents to give your terrarium some personality. But, before you place them inside be sure to clean them with bleach and warm water.
Top the terrarium. This is an entirely optional step. If you want a closed ecosystem, top your terrarium with glass. To find an appropriately sized glass top, take the measurements of the opening of your igloo cooler and find a glass aquarium top that is slightly larger on all sides so that it will sit comfortably on top.