Be sure to have a look at the additional material section and the pdf about how to create an index card system before you start this exercise.
There are many different ways to develop metaphors. For example, check out this really good read:
But always remember:
Start out by first drawing the object and main metaphor. You can use the index cards for this exercise, but feel free to find other styles and shapes according to your personal preference.
After you developed the rough outline and idea of the visual, add details and matching icons to it. These details already indicate how you can use the metaphor later.
On a different card or paper, write down the different meanings of your metaphor and matching icons.
In the end, you created not only a nice visual, but a powerful metaphor, you can use for different purposes. For example: The fruit tree can be a metaphor for a project that is rooted deeply in the company and that will bring some benefits: the apples.
Show the course your ideas and metaphors, that you can use in your business setting!