Jarod and I are getting ready to pour some aluminum this week. We've been working (practically all semester) to get this mold ready. It's 4-part 1000 lb sodium silicate sand mold... it's a monster. Below you see the core on the left and the top part is on the right.
The interior of the mold gets coated with graphite, so the metal can flow smoothly and won't stick to the sand.