The type of terrarium would depend on the type of plants that are going to be housed in it. The plants could be tropical, hilly, desert, mediterannean, exotic etc, the size and scale of the terrarium would depend on the type of plant. Will there be any animals or birds?

A miniature terrarium would require a glass container. Cover its surface with a couple of inches of gravel. Fill up to half the container with the soil of choice. Plant a few plants in the soil. Ensure these are not parasite plants that will suck the moisture of each other. Spray water on the plants. If you want to decorate the terrarium then use natural elements like grass or stone. Do not use plastic or any synthetic material.

A healthy plant will breathe; this will manifest itself as water droplets on the terrarium glass. Use a glass top to cover the terrarium. Do not keep it in direct sunlight and do not over water the plants.

 First, you get a glass tank from the store and then you decorate with suitable plants and other stuff for your animal.