Melt the coconut oil and allow to cool a little. Slowly drop in 1/4 tsp essential oil, one drop at a time. Mix in the arrowroot powder and baking powder (or cornstarch) until smooth.
Pour into an airtight jar and apply with your fingers or a small spatula. Or get yourself an empty deodorant container, (available on line and some homeware stores). When the coconut oil sets (after some time) the deodorant will be in a semi-solid state and ready to use.
These essential oils are antimicrobial, antibacterial, antiseptic, astringent, and anti-inflammatory, and they smell great:
Grapefruit, geranium, lime, cypress, tea tree, lavender, clove, oregano, ylang ylang, frankincense, cedarwood, geranium, tea tree, patchouli, rosemary.