1. A method of imaging a heterogeneous object, the method comprising: positioning the heterogeneous object within a fixture having a chamber, the heterogeneous object comprising a first portion and a second portion, the first portion having the property of attenuating x-rays more than the second portion; adding an inert gas to the chamber, the inert gas comprising at least one of argon, xenon, and krypton; sealing the chamber to substantially contain the gas within the chamber; increasing the pressure within the sealed chamber as a function of the density of the second portion of the object, the density of the gas increasing with the increased pressure within the sealed chamber; penetrating x-rays through the object to produce a plurality of images of the object, the pressurized gas contrasting with the second portion of the object in at least some of the plurality of images; and generating a three-dimensional representation of the object using the contrast produced by the pressurized gas in the plurality of images.