Well, durign the gold rush people had "rushed" all the way to California from all over the world. (Even china!) Ultimately they found nothing- thus made nothing. However, the people who did make something out of nothing were merchants. Mainly because while people moved across land at a time where resources were scarce what did they need? The essentials to start. Essentials like food, clothing, tools, a place to stay.
Hopefully this helps!