Use either the Mold offsets section or the Mold dimensions section:
In the Mold offsets section, set the width of the offsets in each direction. You can set each offset individually, or you can select the Symmetric checkbox and enter a percentage representing a proportional size of the cavity.
In the Mold dimensions section, enter the length of the mold in the X and Y directions.
Set the thicknesses of the mold plates in the Plate thickness section of the dialog:
Enter the thicknesses of the A and B plates.
To include a floating plate, select the Floating Plate checkbox, and enter a thickness.
In the Mold material section, click Browse and select the required mold material.
Click Apply to view your change, and then click Close.