Three-dimensional printing

A method for three-dimensional (3D) printing, comprising:

• applying a polymeric or polymeric composite build material;
• negatively patterning some of the polymeric or polymeric composite build material to define a removable build material portion, the negatively patterning including:
• selectively applying an anti-coalescing polymer solution including a polymer having a pendant reactive functional group;
• and
• selectively applying an anti-coalescing crosslinker solution including a multifunctional crosslinker;
• wherein the pendant reactive functional group and the multifunctional crosslinker react to form an insoluble gel network among the polymeric or polymeric composite build material in the removable build material portion;
• selectively applying a fusing agent on some other of the polymeric or polymeric composite build material to define a portion of the polymeric or polymeric composite build material that is to form part of a final 3D object, and wherein the removable build material portion is at least partially adjacent to the portion;
• exposing the polymeric or polymeric composite build material to radiation to fuse the polymeric or polymeric composite build material in the portion to form a layer of the final 3D object, wherein the polymeric or polymeric composite build material in the removable build material portion remains physically separated from the layer;
• and
• repeating the applying of the polymeric or polymeric composite build material, the negatively patterning, the selectively applying of the fusing agent, and the exposing, wherein the repeating forms the final 3D object including the layer and a removable object in contact with at least a portion of the final 3D object, the removable object including the removable build material portion.