Cross Mold by First Impressions Molds. Cross cavity measures 3-3/4 x 2-3/4 x 1/8 inches. First Impressions Molds uses only the highest quality silicone to create molds used for a variety of mediums. The molds are very soft and flexible and can easily go from as high as 450 degrees to the freezer without affecting the mold! Unlike other silicone molds ours are resistant to rips and tears! Best of all, they are odorless and nothing sticks to them.