Question: how to diffuse eucalyptus oil without a diffuser?
Answer: Cotton ball. Simply put a few drops of your oil of choice, or your favorite blend of oils, onto a plain cotton ball. ... 
Spray bottle. Any type of spray bottle will do. ... 
Tissue method. ... 
In the dryer. ... 
On the stove. ... 
Diffuser necklace. ... 
In the bath. ... 
Palm or bottle method.