Step 1:  "Trees" of original wax models are carefully assembled and placed in metal flasks.  These flasks are then "invested;"  a special liquid is poured into the flask and hardens around the wax models.

Step 2:    The flasks are "burnt out"  in the kiln over 24 hours.   Burning out removes excess moisture, melts the wax away and cures the investment.   The picture above shows Stephen removing flasks from the kiln.