Make a dry paste of corn starch (about 1/2 cup) and baking soda (about 2-3 Tbsp) with at least 10 drops of tea tree oil (kills bacteria, fungus and viruses) with 15-25 drops of your favorite essential oil: good options are lavender oil, orange or lemon oil, patchouli or sandalwood, or gardenia. Obviously the cheaper the oil the further it will go to serve you, but you may have a favorite scent you like to splurge on.
Then add just enough coconut oil as a base - you definitely don't want a liquid, but just to make the powder into more of a deodorant paste you can apply with your finger tips.
Store in an airtight container such a Mason jar or a small Tupperware or Glad re-usable storage container.