A fixture for accurately positioning magnetic memory cores in an array has a top surface for receiving agitated magnetic cores and has a bottom surface for connection to a source of vacuum. The fixture comprises a flat rigid laminar metallic plate formed from a plurality of thin flexible sheets, having etched apertures, arranged in top, middle, and bottom groups, all bonded together in precise registry. The sheets of the top group and the sheets of the bottom group are the same in having rectangular apertures each dimensioned to receive a core edgewise to a depth of up to one-half of the outer diameter of the core. The sheets of the middle group have smaller apertures. The useful life of the fixture can be doubled by turning it over when the top surface becomes worn by the abrasive cores.