The lighting effect is done by creating a hollow cube with any light source such as sea lantern or glow stone etc. Then by using only slabs and stairs (I preferably use quartz as it stands out the most) cover the whole on the inside of the cube and do not let any light source through. The effect is only made when the last light source has been covered and then the magic appears. Stairs and slabs let through a certain amount of light whilst normal blocks accept leaves will completely stop it from shining through. Be creative with the design and you can make some interesting visuals. I hope you like it :)