Cut off a piece of heavy duty foil that's 12 inches square. Place the foil onto a table or other flat working surface with the shiny side up.
Stand a 1-by-1-by-2 inch rectangular wooden block in the center of the foil so that it is 2 inches tall.
Fold the foil into neat layers to wrap around the wooden block. Leave the top open, but cover the rest of the block in multiple layers. Make the inside surface next to the wood smooth and without folds, as this will be the mold that creates the surface of your ice.
Slip the block out of the foil mold, keeping the shape of the rectangle. Stand the mold up on a baking or cookie sheet with the open side at the top.
Fill the mold with clear plastic craft beads. Place the cookie sheet with the mold into an oven preheated to 375 degrees Fahrenheit. Bake the mold for 20 minutes, or until all of the beads have melted and condensed into one mass inside the mold.
Remove the cookie sheet from the oven and allow the plastic to cool completely. Peel the foil from the cube to reveal your prop ice cube.