A nebula (from Latin: "mist"; pl. nebulae or nebulŠ, with ligature or nebulas) is an interstellar cloud of dust, hydrogen gas and plasma. It is the first stage of a star's cycle.
These are my tries in making some, following the inspiration and tutorials of Ali aka Moonchilde-Stock.
They have been made using Apophysis, Universe, and Photoshop.
They are available as stock. See the images to read the comments about rules