The Image below shows a simulation of one of the four processes of the machine the Freezing Unit. The model was used as a construction plan. A copper pipe is bend around a tube to create a spiral, which is isolated from outside and connected via flexible tubes to a modified freezer. That allows a cooled liquid (-10° C) to be pumped to the spiral to freeze the ice core inside of the tube. You can find below each step of building process of the different parts for the prototype.
Final Prototype "Freezing Unit"
Insulated Flexible Tube