We derive gravity equations from three different general equilibrium models incorporating multinational firms. We show that gravity equations are particularly adapted to the analysis of foreign affiliates' activities of multinational firms. However, the different theoretical models lead to...

This paper analyzes the effects of 3D printing technologies on the volume of trade and on the structure of FDI. A standard model with firm-specific heterogeneity generates three main predictions. First, 3D printers are introduced in areas with high economic activity that also face high transport...