The element Glass is often used in Little Alchemy 2, and you could combine Aquarium, Crystal Ball, Glasses, Greenhouse, Hourglass, Light Bulb, Mirrow, and Snow Globe with Glass. Making Glass is easy, and we have figured out the easiest way to achieve the goal. Although there are other methods, but it will surely more complicated and I do not think you need to waste time on that. Check out the below instruction and feel free to make your own Glass.
Air + Air = Pressure
Earth + Pressure = Stone
Air + Stone = Sand
Sand + Fire = Glass