The invention provides an ion trap assembly. In general terms, the ion trap assembly contains: a) a segmented linear ion trap; b) an insulator disposed around the segmented linear ion trap; and c) a bonding material for attaching and spacing the insulator and said segmented linear ion trap. The ion trap assembly is generally made by mounting an elongated conductive workpiece to a set of rigidly connected insulators using a bonding material, and cutting the elongated conductive workpiece into a plurality of rods using wire electrical discharge machining. Also provided is a mass spectrometry system containing the precision segmented linear ion trap.