Baking Soda Crystal Growing Tree You'll Need: Paper Christmas tree cutouts (Two matching pieces with slits so they interlock and stand upright work best. Cardstock or thick paper gives the strongest results.) Tray, shallow bowl, or glass dish Epsom salt (recommended for fast, dramatic crystal growth) You may substitute baking soda or table salt, but crystals will grow slower and less fluffy Warm water Food coloring (multiple colors) Small cups for mixing colors Paintbrush or dropper Scissors and