Humans have a Subconscious desire for continuity and by linking the product at hand with the place/ingredients/contributors from which it is made you help them connect what\’s outside with what\’s inside. (Young S. , 2004) (Winnett & Pohlmann, 2011) (Block, 1995)

Because of this, try to find ways to bring the inside to the outside

A great example of this is Babees Honey.

The Doritos concept box above is an excellent example of this type of thinking. While most chips are round, Doritos have always stood out due to their triangular shape. This designer leveraged that trait and used triangles heavily to define shape of the box. (Young S. , 2004)

Another great example of this comes from Domestos with their sink and pipe unblocker.

References
Block, P. H. (1995, July). Seeking the ideal form: Product design and consumer response. Journal of Marketing.

Winnett, C., & Pohlmann, A. (2011). Neuromarketing: Understanding the Subconscious Drivers. NeuroFocus, The Nielsen Company.

Young, S. (2004, Winter). Breaking Down the Barriers to Packaging Innovation. Design Management Review.