Different ways to create nebulas?

Sastrei

Broad question, I know, but what are some different ways to create the classic colorful space nebula? I'd like to create some for background elements on a skysphere, but I lack the artistic ability to paint 2D nebulas by hand. I was thinking volumetric sims, but those are resource intensive and I don't know a lot about them, plus I usually end up finding smoke/fire/water tutorials instead that are geared towards a dynamic effect rather than a static one.

rube

If you happen to be using maya you should find some galaxy type stuff in the visor for fluids.

Valandar

There's also countless filters on Filter Forge that can be made seamless, and tweaked and altered, or even torn apart to see how they work, that create nebulae for 2D elements.

Eric Chadwick

Neat article about Homeworld's gorgeous nebulas.
https://simonschreibt.de/gat/homeworld-2-backgrounds/

Aabel

Depending on how much time you have to learn new software, the particle, gas and fluid solvers in Houdini would be a great choice for this task, there's also a pretty easy shelf tool for making clouds that can be massaged into nebulas. You will get high quality results with a high degree of control.

RN

http://web.archive.org/web/20030710022308/http://gallery.artofgregmartin.com/tuts_arts/making_a_star_field.html

This tutorial is a classic, you learn some fundamental tricks with it.
You can follow with Photoshop or Krita etc., and if you don't have a graphics tablet you can still use your mouse, just use a low brush flow.

EDIT: Now that I read it again I realise that, in the part where he recommends using the Clone Stamp tool to make thicker star clusters, you can achieve the same or better effect by using a custom brush preset with a small radius and large scattering with jitter, along with brightness jitter. Kinda like a spray brush.