Three-dimensional printing

1 . A kit for 3D printing, the kit comprising:

build material particles comprising metal-containing particles and/or ceramic particles;

a jettable marking agent consisting of marking component nanoparticles dispersed in a non-aqueous liquid carrier, wherein the marking component nanoparticles are selected from the group consisting of:

pure metal nanoparticles selected from the group consisting of magnesium nanoparticles, aluminum nanoparticles, titanium nanoparticles, niobium nanoparticles, tantalum nanoparticles, vanadium nanoparticles, palladium nanoparticles, platinum nanoparticles, copper nanoparticles, silver nanoparticles, gold nanoparticles, cadmium nanoparticles, zinc nanoparticles, lead nanoparticles, and combinations thereof;

metal oxide nanoparticles selected from the group consisting of Al 2 O 3 , TiO 2 , Y 2 O 3 , ZnO, and a combination thereof; and

ceramic nanoparticles,

wherein the marking component nanoparticles are i) different from the build material particles and ii) combinable with the build material particles to form an alloy or composite material during 3D printing; and

a binding agent comprising a metal-containing binder dispersed in a liquid carrier,

wherein when the marking component nanoparticles comprise the pure metal nanoparticles or the metal oxide nanoparticles, the metal-containing binder is different from the pure metal nanoparticles or the metal oxide nanoparticles of the marking agent.

2 . The kit according to claim 1 , wherein:

the build material particles are metal-containing particles, and wherein the metal-containing particles comprise copper-containing particles; and

the marking component nanoparticles are pure metal nanoparticles, and wherein the pure metal nanoparticles are silver nanoparticles.

3 . The kit according to claim 1 , wherein the build material particles are the metal-containing particles, and wherein the metal-containing particles are the same as the metal-containing binder.

4 . The kit according to claim 1 , wherein the metal-containing binder is a metal salt.

5 . The kit according to claim 1 , wherein the marking component nanoparticles are the pure metal nanoparticles.

6 . The kit according to claim 5 , wherein the pure metal nanoparticles are selected from the group consisting of aluminum nanoparticles, titanium nanoparticles, niobium nanoparticles, tantalum nanoparticles, vanadium nanoparticles, magnesium nanoparticles, cadmium nanoparticles, lead nanoparticles, and combinations thereof.

7 . The kit according to claim 1 , wherein the marking component nanoparticles are the metal oxide nanoparticles.

8 . The kit according to claim 7 , wherein the metal oxide nanoparticles are selected from the group consisting of Al 2 O 3 , TiO 2 , Y 2 O 3 , and a combination thereof.

9 . A method of three-dimensional (3D) printing a 3D printed object, the method comprising:

selectively jetting a marking agent onto a first region of a layer of build material, wherein the build material comprises build material particles comprising metal-containing particles and/or ceramic particles, and wherein the marking agent consists of marking component nanoparticles dispersed in a non-aqueous liquid carrier with the marking component nanoparticles selected from the group consisting of:

pure metal nanoparticles selected from the group consisting of magnesium nanoparticles, aluminum nanoparticles, titanium nanoparticles, niobium nanoparticles, tantalum nanoparticles, vanadium nanoparticles, palladium nanoparticles, platinum nanoparticles, copper nanoparticles, silver nanoparticles, gold nanoparticles, cadmium nanoparticles, zinc nanoparticles, lead nanoparticles, and combinations thereof;

metal oxide nanoparticles selected from the group consisting of Al 2 O 3 , TiO 2 , Y 2 O 3 , ZnO, and a combination thereof; and

ceramic nanoparticles;

wherein the marking component nanoparticles are i) different from the build material particles and ii) combinable with the build material particles to form an alloy or composite material;

selectively jetting a binding agent onto at least a portion of the layer of the build material, the binding agent comprising a metal-containing binder dispersed in a liquid carrier, wherein when the marking component nanoparticles comprise the pure metal nanoparticles or the metal oxide nanoparticles, the metal-containing binder is different from the pure metal nanoparticles or the metal oxide nanoparticles of the marking agent; and

binding the build material particles such that the marking component nanoparticles are incorporated into the 3D printed object in a predetermined arrangement and forms a detectable marker in the 3D printed object.

10 . The method according to claim 9 , further comprising sintering the build material after the binding.

11 . The method according to claim 9 , wherein the detectable marker is not detectable by visual inspection of the 3D printed object.

12 . The method according to claim 9 , wherein the detectable marker has characteristic magnetic properties and/or a characteristic hardness.

13 . The method according to claim 9 , wherein the detectable marker has a characteristic response to treatment with a chemical agent.

14 . The method according to claim 9 , wherein the detectable marker has a magnetic signature including encoded data that enables the 3D printed object to be identified, located, and/or tracked.

15 . The method according to claim 14 , wherein the detectable marker includes data in machine-readable form.