Three-dimensional (3d) printing

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

• a supply of storage-stable build material, including:
• a plurality of first reactive particles;
• a plurality of second reactive particles, the first and second reactive particles to mutually react with each other upon contact therewith;
• and
• a coating on:
• i) the plurality of first reactive particles;
• or
• ii) the plurality of second reactive particles;
• or
• iii) both i) and ii);
• the coating providing isolation between the plurality of first reactive particles and the plurality of second reactive particles, to prevent mutual reaction therebetween during storage of a mixture of the plurality of first reactive particles and the plurality of second reactive particles;
• a build material distributor;
• a supply of fluid;
• an inkjet applicator for selectively dispensing the fluid;
• a controller;
• a non-transitory computer readable medium having stored thereon computer executable instructions to cause the controller to:
• utilize the build material distributor to dispense a layer of the build material;
• and
• utilize the inkjet applicator to selectively dispense the fluid onto a selected area of the layer of the build material, wherein:
• the fluid disrupts the coating on the selected area of the layer of the build material to render the first and second reactive particles in the selected area in contact with each other, the contact initiating mutual reacting between the first and second reactive particles;
• and
• the mutual reacting fuses the first and second reactive particles together over the selected area.