Abstract: A three-dimensional printer uses inkjet-type printheads to rapidly prototype, or print, a three-dimensional model. A powder feeder includes a conveyor system and a metering system to deliver powder to a build area in measured quantities. The powder feeder also includes a vacuum system for loading powder into a feed reservoir or chamber. The vacuum system can also be used to cleanup excess powder. Other powder control features include powder gutters and magnetic powder plows. During printing, a cleaning system operates to remove powder from the printheads. In the event of a printhead or jet failure, the failure can be detected and corrective measures taken automatically. After printing, the model can be depowdered and infiltrated in an enclosure.