The merchant replies "You can take a look, sure. No borrowing, though."

He opens a chest and takes out a Handy Haversack, then takes some tuning forks out of that.

He shows you forks of copper, zinc, lead, and tin. "Fire, Earth, Water, Air." He taps them and they each emit a tone.

Then steel, iron, and lead. "A Prime, the Waste, and Shadow."