How do you make an ecosystem in a bottle?

To create an ecosystem in a bottle, start with a clear glass or plastic container with a lid. Layer small stones or gravel at the bottom for drainage, followed by activated charcoal to filter the water, and then add a layer of potting soil. Plant small, hardy plants like moss or ferns, and add a small amount of water. Seal the bottle to create a self-sustaining environment, placing it in indirect sunlight to avoid overheating.