Research how the ecosystem you would like to make looks and what types of animals and plants live there. Plan what you would like to include in the box.
Remove the lid from the box. Cut the edges of the box if the box is deep and makes it uncomfortable to work in. The bottom of the box will become the "stage."
Cut a piece of white paper big enough to fit the "stage" in the box and glue in place. Cut four pieces of white paper to glue in the inside top, bottom, left and right sides of the "stage." Glue them in place.
Draw the landscape. Use crayons, paint or markers to draw the scenery of the habitat. Draw not only on the "stage" but also on the inside sides of the box to create a complete image. Include the sky, plants and the ground.
Add details to the landscape using various materials depending on the ecosystem chosen. Glue dry grass or Easter grass on the bottom of the box, add cotton balls for snow and clouds, glue sand and rocks, make seaweed out of constructions paper, glue empty egg cartons for icebergs, paint cotton balls green for the trees, glue flowers, use stickers or make items out of play dough.
Add animals to the ecosystem. Glue little toy animals, print some from the computer or create your own. Draw animals in card stock, cut them and glue them to the box or hang them from the roof of the box using yarn. Or, create animals out of play dough, paint them when they are dry and glue them to the box.