Black and Tan perfect pour ice mold

This is a design for a 3d-printable ice mold used to make perfect black and tans.
The mold can be filled with water and frozen to make an ice disk with a hole in it. The disc can then be placed into a pint glass, and the Bass or Harp beer is poured in first. It flows through the hole in the ice disk until the glass is filled to the bottom of the disk. The Guinness is then poured on top, and stays separated. The ice melts, and you end up with a perfect pour.
The OD of the disk could be adjus