Answer:
Bridging social capital
Explanation:
As people that attended the conference comes from all walks of life, it means they are from diverse background. However, the 3D printing technology focused on bringing them together, which means they are from heterogeneous background to homogeneous environment. This is exactly what is called BRIDGING SOCIAL CAPITAL.
BRIDGING SOCIAL CAPITAL is a type of social capital that focused on uniting or linking people of different background, race, knowledge, class or religion together to have or form one objective for the purpose of achieving one goal.