I tried different test but not enough satisfying… I would like to create realistics renders of bricks like in the following pictures, I let a little sketch which explain the physic principle of how this type of brick is made, I would maybe have an approach where the object is physicly correct, glass thickness is 5mm, the general dimension of the brick is 21,5 cm long / 6.5cm height /11,5cm . Another detail : if you observe well the brick has 2 different kind of bump, one for the glass and an other one bigger in scale on the metal layer behind…
I think you need two objects (deformed cuboids), one for the outer glas shape and one for the metal inner shape. Both should get an own bump structure. For the glass I would use the fog parameter. In a HDRI environment placed it could be nice looking.
