Three-dimensional printing and three-dimensional printers

A system for printing at least one three-dimensional object, comprising:

• a processing chamber comprising an internal processing chamber volume that is configured to facilitate printing of the at least one three-dimensional object in a first atmosphere in the internal processing chamber volume;
• a build module having an opening and a build module volume that is configured to accommodate the at least one three-dimensional object;
• and
• a shutter operatively coupled to the build module, which shutter is configured to close the opening to seal the build module to maintain a second atmosphere in the build module volume at a positive pressure above an ambient pressure,
• which processing chamber and build module are configured to reversibly attach and detach from one another,
• wherein upon detachment of the build module and the processing chamber from one another, the shutter is configured to seal the build module to maintain the second atmosphere at the positive pressure above the ambient pressure.