A method for forming a part. The method includes: forming a first portion of the part at a first level; forming a second portion of the part at a second level; wherein forming the first and second portions includes exposing the first and second levels to a sintering process and portions of the first and second levels to an electron beam; forming a wire in the passage formed inside the first and second portions by exposing a portion of the passage to the electron beam; applying a signal to the wire to break up sintered material in the passage; and removing the wire.