We eagerly await any news. Your team deserves great praise and encouragement. Development of a practical modern approach to creation of Lippmann images would be a significant advance.
I work in the field of adaptive optics where we measure (and alter) the phase of the light waves to correct for aberrations due to optics and atmosphere. We sometimes use volume diffraction gratings to create a sample of the optical wavefront we want to measure. These gratings are very similar in structure to a finished Lippmann plate being formed by three dimensional index variations in a transparent medium. They are typically made using materials like the photopolymer mentioned in holmburgers recent post or from photochromic glass. These aren't suitable for the Lippmann process because they require quite intense optical beams for creation (i.e. lasers). The real trick for a Lippmann plate is to record the standing waves set up by the interference of light with its reflection off the back interface of the plate in a reliable and reproducible way and to avoid all the problems with absorption and scattering that reduce the contrast of the image.
Good luck with your research!