Several kinds of wastes have been converted into glasses, successively powdered and sintered with simultaneous crystallisation. The employed “sinter-crystallisation” process was useful to obtain glass-ceramics with particular crystal phases (sometimes un-accessible from traditional nucleation/crystal growth treatments, like feldspar crystals). Conventional pressing of fine glass powders led to monoliths, after sintering, with remarkable mechanical properties (for example bending strength exceeding 100 MPa), useful for tile applications; replication processes, by employing sacrificial polymeric materials, after the same thermal treatment employed for the monoliths, led to open-celled glass-ceramic foams, useful for filtering applications. The enhanced specific surface due to porosity was found to have a positive effect on crystallisation.