Mix dry ingredients: In a medium bowl, combine coarse salt, sugar, ground oats, and lemon zest until evenly blended.
Add oils: Stir in a neutral liquid oil of your choice and your essential oils. Slowly add melted coconut oil, mixing until the scrub is thick and moist but not wet. To adjust, add a bit more oil if too dry, or a little more salt/sugar if too wet.
Jar and store: Spoon the scrub into a clean, dry, airtight jar. Store at room temperature for 1–2 months, keeping water out to maintain freshness.