Material manipulation in additive manufacturing

A device for separating powder, the device comprising:

• a first separating unit coupled to a second separating unit at least in part by a channel configured to facilitate pressure equilibration and flow of the powder;
• a first collection container operatively coupled to the first separating unit at least in part by a first valve;
• a second collection container operatively coupled to the second separating unit at least in part by a second valve;
• and
• a third collection container operatively coupled to (a) the first collection container at least in part by a third valve, and (b) the second collection container at least in part by a fourth valve,
• each of the first valve, second valve, third valve, and fourth valve, is configured to have an open state and a closed state, the open state being configured to facilitate flow of powder therethrough and to facilitate pressure equilibration therethrough, and the closed state being configured to deter, or stop (i) the flow of the powder therethrough and (ii) the pressure equilibration therethrough, the device being configured to facilitate directional powder flow based at least in part on one or more pressure differentials,
• wherein during operation, the device is configured to enclose and to maintain, one or more atmospheres having positive pressure above ambient pressure external to the device, and wherein the device is configured to deter, or prevent, flow of the powder (I) from the first collection container to the first separating unit, (II) from the second collection container to the second separating unit, and (III) from the third collection container (A) to the first collection container, (B) to the second collection container, or (C) to the first collection container and to the second collection container.