Sand casting a long pulley half for a rare Maserati car. The casting uses two CO2 silicate cores, one of which is placed inside the other. This "inside" core is made from two identical pieces and is glued up around a central brass tube that itself forms part of the core in contact with the metal being cast. The brass tube provides much of the necessary venting for the core.
This was not the easiest job that I have ever done!