Ice cube trays are available in several different materials, including plastic, silicone, and stainless steel. Choose the material that best fits your needs. You can also find trays that make ice in a variety of shapes. A cube shape is obviously the classic option, but you may prefer a tray that makes heart, star, fish, or other novelty-shaped cubes for a party or special occasion.  Plastic ice cube trays are the least expensive and durable. They may absorb freezer odors and crack when you remove the ice. Silicone ice cube trays are more expensive, but they're durable and don't crack. They tend to absorb freezer odors the most. Stainless steel trays are the most expensive and durable, but they also don't absorb any odors. Wooden ice cube trays can be very inexpensive if you make them yourself. They make the highest-quality ice cubes. Mix 2 teaspoons (10 g) of baking soda with ½ cup (120 ml) of warm water. Pour the solution into the tray, then scrub all of the wells with a clean cloth. Rinse the tray with warm water, then allow it to dry. If your tray produces off-tasting ice cubes, that means it has absorbed odors from the freezer. Washing it with this baking soda solution will help fix that. Once the tray is washed and dried, fill it with water. Try to pour the same amount of water into each compartment so the cubes will all freeze in the same amount of time.  You can use tap water, but be aware that the minerals in the water can give you cloudy, poor-tasting ice cubes. Filtered or bottled water typically produces better-tasting ice cubes than tap water, but be aware that the ice may still look cloudy. If you want crystal clear ice, boil the water first. Let it cool, boil it a second time, then use it to fill the tray. The hot water will freeze much faster as well.

Summary:
Choose the right tray. Deodorize old ice trays to reduce off-flavors, if needed. Fill the tray with water.