Homemade Peppermint and Eucalyptus Shower Melts: Mix 1/3 cup of water into 1 cup of baking soda. Add in 20 drops of eucalyptus oil and 20 drops of peppermint oil. Put in mini muffin pan. Bake for 20 minutes at 350. Place furthest away from shower head. After, pour vinegar down drain to clean out drain.