Because the printer needs besides changing the toolhead, replacing the controller with one capable of dual extruder operation and finding a place for the material no other modification, I think it's a good idea to use a budget printer like the Ender 3 Pro or similar to work with.

The only thing to watch out for is to use not too much acceleration in the Y axis to prevent distortion of the printed powder/sand layers.

The next thing will be finding out the startcode for homing and probing of the graphite crucible. I added probe connections to the steel rod and the crucible which will trigger at contact. The startcode should probe the crucible to find out its center (X0, Y0) and its bottom (Z0).