And the Lord said to Moses, Take to you sweet spices,
• drippy spice (storax), and
• shiny spice (onycha), and
• fatty spice (galbanum);
these sweet spices with pure frankincense

Rashi explains that
• Storax is called drippy spice because it is typically obtained when it oozes from the tree;
• onycha is called shiny spice because of its shiny appearance; I would therefore extend Rashi's method and explain:
• Galbanum is called fatty spice because it smells bad like putrid fat.

Rashi makes symbolic inferences from the use of a bad smelling fatty spice in the sweet incense: #####

We can extend Rashi's symbolism as follows:
• The shiny spice obviously symbolically refers to a shiny flashy person who is always conspicuous and showing off;
• We have just seen that the fatty spice symbolizes foul-smelling people, people who are bad. Since you become fat by always indulging perhaps the fatty spice symbolizes indulgers; and
• Finally the drippy spice would refer to a stately person who does things drop by drop (bit by bit) and not hurriedly.
Together, the three spice types listed in Ex30-34--the drippy, fatty, and shiny---would correspond to three basic types of people: the stately, the indulgers and the flashy people. We could say more but the just-stated explanation gives the flavor of how Rashi's symbolism can be understood and extended in a natural way.