Choose a carbon-rich material such as coconut shells, hardwood, or peat
Dry the material completely
Heat the material in a low-oxygen environment to make charcoal
Crush the charcoal into small pieces or powder
Mix the charcoal with an activating agent such as steam, carbon dioxide, or a chemical activator
Heat it again at high temperature to create pores
Rinse the activated charcoal thoroughly if a chemical activator was used
Dry the activated charcoal completely
Store it in an airtight container