I also like how you regularly point out that there are layers to effective protoyping … sketching, small-scale protoyping, sketching, large-scale protoyping, evaluation, more sketching, etc. Just because a product is being refined doesn’t mean that less refined exploration methods should go away.

Additional points that Mark makes that resonate with me are, that as we flesh out and improve prototypes/designs, some primary goals are 1) affordability (which more loosely is ease of entry or involvement), increased functionality, and increased simplicity.

Thanks for sharing.