Different mixtures of build materials deliverable during a three dimensional print operation

A system, comprising:

• a three dimensional (3D) print apparatus comprising a delivery hopper connected to a source of a first build material and a source of a second build material;
• and
• a controller of the 3D print apparatus to direct that:
• a first quantity of the first build material and a second quantity of the second build material is receivable by the delivery hopper;
• a first mixture of a received first quantity and second quantity of build materials is deliverable to a print zone of the 3D print apparatus from the delivery hopper for formation of a first region associated with an object in the print zone;
• a third quantity of the first build material and a fourth quantity of the second build material is receivable by the delivery hopper;
• and
• a second mixture of a received third quantity and fourth quantity of build materials is deliverable to the print zone of the 3D print apparatus from the delivery hopper for formation of a second region associated with the object in the print zone;
• and
• wherein the first mixture includes a proportion of the first build material relative to the second build material that is different than that included in the second mixture.

A method, comprising:

• selectively receiving by a delivery hopper of a three dimensional (3D) print apparatus, from a plurality of connected build material hoppers, at least one of a first build material and a second build material, which is different from the first build material, during a 3D print operation;
• delivering from the delivery hopper to a print zone of the 3D print apparatus either the selected first build material, the selected second build material, or a selected mixture of the first build material and the second build material;
• and
• forming regions in the print zone according to a print protocol during the 3D print operation, wherein a first region is formed from the selected second build material and a second region is formed from either the selected first build material or the selected mixture.