We print out page designs, hand them some scissors, and get them to cut up the pages into their smallest components. Mix them all up so you can’t even tell which components came from which pages.
I really like this workshop exercise idea from Charlotte and Jeremy. I do something similar in my company workshops with my interface inventory exercise, but I have everyone screenshot their existing sites or new designs. The tangible nature of printing something out and chopping it up definitely seems like an effective way to sell people on a pattern-based design and development workflow.