A processing machine (10) for building an object (11) from material (12) includes (i) a material bed assembly (16) that supports the material (12); (ii) a material supply assembly (18) that positions the material (12); (iii) an energy system (22) that directs an energy beam (22A) at the material (12) to build the object (11); (iv) a housing assembly (24) that defines at least a portion of a build chamber (29) for the energy beam (22A), the housing assembly (24) being spaced apart a housing gap (30A) from the material (12); and (v) a seal assembly (26) that creates a housing seal (26A) between the housing assembly (24) and the material (12) to seal the housing gap (30A).