According to examples, an apparatus may include an agent delivery device to deliver a coalescing agent to selected locations of a build material layer and a plurality of microwave energy emitters, each of the microwave energy emitters including a tip to generate a focused microwave energy field onto a respective area near the tip, in which the tip is to be positioned to place a portion of the build material layer within the focused microwave energy field. The apparatus may also include a controller that may control the microwave energy emitters to direct microwave energy onto the build material layer.