A microelectronic interposer is made by providing a sacrificial layer over the surface of a planar body. Apertures are formed passing through the body and the sacrificial layer. A layer of an electrically conductive structural material is deposited in each of the apertures and over the sacrificial layer, proximate to each aperture to thereby form contacts. The sacrificial layer is removed leaving the contacts with outwardly flaring peripheral portions spaced vertically above the surface of the planar body.