Step 7: Make the Second Half of the Mold
Once the sand for the first half of the mold has cured (I typically allow it to cure overnight), you can flip the piece over to create the second half of the mold.
Carefully line up the second half of the pattern on top of the first half that is now surrounded by the sand. Ressamble the flask to make a frame for adding the second batch of sand.
Be certain to heavily apply cornstarch to ensure that the two halves of the mold can be separated. Remember, you still need to open it back up to remove the pattern.