We propose a simple and reliable solid phantom for mimicking localized absorption changes within a diusive medium. The phantom is based on the Equivalence Relation stating that any realistic absorption inhomogeneity can be mimicked by a totally absorbing sphere of adequate volume. Applying this concept, we constructed a solid phantom holding a movable black inclusion to be positioned beneath the source-detector pair (perturbed case) or far from it (unperturbed case). Dierent absorption perturbations can be mimicked by changing the volume and the position of the black object both in transmittance and reflectance conguration. Time-resolved measurements of transmittance images and a lateral reflectance scan are presented.