Decarboxylate cannabis by spreading it on a baking sheet and heating it at 220–240°F (105–115°C) for 30–45 minutes
Grind the decarboxylated cannabis coarsely
Combine the cannabis with a cooking oil such as coconut oil, olive oil, or avocado oil in a slow cooker, double boiler, or saucepan on very low heat
Use about 1 cup of oil for every 1 cup of ground cannabis, adjusting as needed
Keep the mixture at low heat for 2–6 hours, stirring occasionally and avoiding boiling
Strain the mixture through cheesecloth, a fine mesh strainer, or a nut milk bag into a clean container
Squeeze out the remaining oil from the plant material
Let the oil cool completely
Store the canna oil in an airtight container in a cool, dark place or refrigerate it