Wayfarers
Young dwarves who go on the road in itinerant groups, each carrying a dwarven craft with it.
On the road
Many dwarves go on the road when young as itinerant groups of dwarven engineers. Some of those groups would have the capability to build hardcast structures, for high profit.
Wayfarers
The itinerant groups are known as Wayfarers, and are in general welcomed by Markish culture. Some Wayfarers are artillery manufacturers, some are hardcast specialists, some are stonemasons, and some are weaponsmiths. Just about every dwarven craft has been taken on the road by Wayfarers at some point.
The trope
"Returning home with my First Ingot" is a cultural trope among dwarves.
See also: Artillery, First Ingot, Hardcast Works, Without a First Ingot