Abstract: The present disclosure is drawn to 3-dimensional printed parts that can include a conductive composite portion and an insulating portion. The conductive composite portion can include a matrix of fused thermoplastic polymer particles interlocked with a matrix of sintered elemental transition metal particles. The insulating portion can include a matrix of fused thermoplastic polymer particles that are continuous with the matrix of fused thermoplastic polymer particles in the conductive composite portion. The insulating portion can be substantially free of sintered elemental transition metal particles and can include transition metal oxide bronze particles.

Abstract: A strain sensor can include a resistor, a first electrical contact at a first end of the resistor, and a second electrical contact at a second end of the resistor. The resistor can be formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles.

Abstract: The present disclosure is drawn to 3D printing kits, multi-fluid kits for 3D printing, and methods of making 3D printed articles. In one example, a 3D printing kit can include a powder bed material, a fusible fluid, and a magnetic fluid. The powder bed material can include polymer particles. The fusible fluid can include water and a radiation absorber. The fusible fluid can be to selectively apply to the powder bed material. The magnetic fluid can include magnetic particles, and the magnetic fluid can be to selectively apply to the powder bed material.

Abstract: The present disclosure is drawn to 3D printing kits, multi-fluid kits for 3D printing, and methods of making 3D printed articles. In one example, a 3D printing kit can include a powder bed material, a fusible fluid, and a magnetic fluid. The powder bed material can include polymer particles. The fusible fluid can include water and a radiation absorber. The fusible fluid can be to selectively apply to the powder bed material. The magnetic fluid can include magnetic particles, and the magnetic fluid can be to selectively apply to the powder bed material.

Abstract: The present disclosure is drawn to 3-dimensional printed parts that can include a conductive composite portion and an insulating portion. The conductive composite portion can include a matrix of fused thermoplastic polymer particles interlocked with a matrix of sintered elemental transition metal particles. The insulating portion can include a matrix of fused thermoplastic polymer particles that are continuous with the matrix of fused thermoplastic polymer particles in the conductive composite portion. The insulating portion can be substantially free of sintered elemental transition metal particles and can include transition metal oxide bronze particles.

Abstract: The present disclosure is drawn to material sets for 3-dimensional printing. The material set can include a thermoplastic polymer powder having an average particle size from 20 ?m to 200 ?m, a conductive fusing agent composition including a transition metal, and nonconductive fusing agent composition. The nonconductive fusing agent composition can include transition metal oxide bronze particles.

Abstract: The present disclosure is drawn to 3D printing kits, multi-fluid kits for 3D printing, and methods of making 3D printed articles. In one example, a 3D printing kit can include a powder bed material, a fusible fluid, and a magnetic fluid. The powder bed material can include polymer particles. The fusible fluid can include water and a radiation absorber. The fusible fluid can be to selectively apply to the powder bed material. The magnetic fluid can include magnetic particles, and the magnetic fluid can be to selectively apply to the powder bed material.

Abstract: A strain sensor can include a resistor, a first electrical contact at a first end of the resistor, and a second electrical contact at a second end of the resistor. The resistor can be formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles.

Abstract: A strain sensor can include a resistor, a first electrical contact at a first end of the resistor, and a second electrical contact at a second end of the resistor. The resistor can be formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles.

Abstract: According to an example, a three-dimensional (3D) printed heater may include a part body formed of fused thermoplastic polymer particles and an electrically resistive element formed of a matrix of conductive particles interspersed between a matrix of thermoplastic polymer particles. The conductive particles and the thermoplastic polymer particles may be provided at respective densities to cause the electrically resistive element to have a predetermined resistance level. The 3D printed heater may also include electrical contacts connected to the electrically resistive element, in which a current is to be applied through the electrically resistive element via the electrical contacts to cause the electrically resistive element to generate a predefined level of heat.

Abstract: The present disclosure is drawn to material sets for 3-dimensional printing. The material set can include a thermoplastic polymer powder having an average particle size from 20 ?m to 200 ?m, a conductive fusing agent composition including a transition metal, and nonconductive fusing agent composition. The nonconductive fusing agent composition can include transition metal oxide bronze particles.

Abstract: A strain sensor can include a resistor, a first electrical contact at a first end of the resistor, and a second electrical contact at a second end of the resistor. The resistor can be formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles.

Abstract: According to an example, a three-dimensional (3D) printed heater may include a part body formed of fused thermoplastic polymer particles and an electrically resistive element formed of a matrix of conductive particles interspersed between a matrix of thermoplastic polymer particles. The conductive particles and the thermoplastic polymer particles may be provided at respective densities to cause the electrically resistive element to have a predetermined resistance level. The 3D printed heater may also include electrical contacts connected to the electrically resistive element, in which a current is to be applied through the electrically resistive element via the electrical contacts to cause the electrically resistive element to generate a predefined level of heat.