A three-dimensional printing method, comprising: applying a first layer of a build material; patterning a part layer by selectively applying a penetrating liquid functional material on at least a portion of the first layer, the penetrating liquid functional material, including: a first oxide nanoparticle, which includes a metal or a semi-metal atom and at least one oxygen atom, wherein the first oxide nanoparticle has a particle size ranging from about 0.5 nm up to 10 nm, the first oxide nanoparticle present in an amount ranging from about 5% to about 15% by weight based on a total weight of the penetrating liquid functional material; a second metal oxide nanoparticle having at least one dimension greater than 10 nm, the second metal oxide nanoparticle present in an amount ranging from about 0.25% to about 10% by weight based on the total weight of the penetrating liquid functional material; an electromagnetic radiation absorber in an amount ranging from about 1% to about 10% by weight based on the total weight of the penetrating liquid functional material; an organic solvent in an amount from about 5% to about 50% by weight based on the total weight of the penetrating liquid functional material; a surfactant; and a balance of water; and exposing the first layer having the penetrating liquid functional material applied thereon to electromagnetic radiation, whereby the portion of the first layer at least partially fuses to form the part layer. applying a first layer of a build material; patterning a part layer by selectively applying a penetrating liquid functional material on at least a portion of the first layer, the penetrating liquid functional material, including: a first oxide nanoparticle, which includes a metal or a semi-metal atom and at least one oxygen atom, wherein the first oxide nanoparticle has a particle size ranging from about 0.5 nm up to 10 nm, the first oxide nanoparticle present in an amount ranging from about 5% to about 15% by weight based on a total weight of the penetrating liquid functional material; a second metal oxide nanoparticle having at least one dimension greater than 10 nm, the second metal oxide nanoparticle present in an amount ranging from about 0.25% to about 10% by weight based on the total weight of the penetrating liquid functional material; an electromagnetic radiation absorber in an amount ranging from about 1% to about 10% by weight based on the total weight of the penetrating liquid functional material; an organic solvent in an amount from about 5% to about 50% by weight based on the total weight of the penetrating liquid functional material; a surfactant; and a balance of water; and exposing the first layer having the penetrating liquid functional material applied thereon to electromagnetic radiation, whereby the portion of the first layer at least partially fuses to form the part layer. a first oxide nanoparticle, which includes a metal or a semi-metal atom and at least one oxygen atom, wherein the first oxide nanoparticle has a particle size ranging from about 0.5 nm up to 10 nm, the first oxide nanoparticle present in an amount ranging from about 5% to about 15% by weight based on a total weight of the penetrating liquid functional material; a second metal oxide nanoparticle having at least one dimension greater than 10 nm, the second metal oxide nanoparticle present in an amount ranging from about 0.25% to about 10% by weight based on the total weight of the penetrating liquid functional material; an electromagnetic radiation absorber in an amount ranging from about 1% to about 10% by weight based on the total weight of the penetrating liquid functional material; an organic solvent in an amount from about 5% to about 50% by weight based on the total weight of the penetrating liquid functional material; a surfactant; and a balance of water; and exposing the first layer having the penetrating liquid functional material applied thereon to electromagnetic radiation, whereby the portion of the first layer at least partially fuses to form the part layer.