What AM method allows manufacturers to directly build sacrificial sand molds without the use of a master pattern?

Binder jetting is the correct answer because this additive manufacturing method is specifically designed to create parts directly from powder materials by binding the particles together using a liquid binder. In the case of sand molds, binder jetting allows manufacturers to build these intricate shapes directly from digital models, eliminating the need for a master pattern. The technology enables the layer-by-layer construction of molds, which can be easily removed after the manufacturing process, thus acting as sacrificial components.

This approach offers significant benefits, including reduced lead times, lower material waste, and increased design flexibility compared to traditional sand casting methods that typically rely on making a master pattern first. Other additive manufacturing methods listed, such as fused deposition modeling, selective laser sintering, and direct metal laser sintering, do not focus on creating sand molds in the same manner, and often require patterns or specific setups that are not directly applicable to the process of building sacrificial molds.