Hello!
Here's a step-by-step sequence of recent Samus picture (original lineart by Legoman)
The process was kind of similar to the one that i've used for Hilda picture - a 3d background that i slightly overpainted in order to add some details. And of course DoomSlayer made with 3d tools too, original model for XNALARA can be found on Diegoforfun's page
It was a bit tricky to make all the components (characters and background) work together so i had to go back and forth between Photoshop and Blender and make additional renders with slightly different poses, camera angles and lighting to achieve a desired look.
I'll probably make a video tutorial on how to use Blender in case you'd like to try to add 3d background to your pictures
And of course if you'd have any questions about the coloring process - please let me know! You can either reach me here in the comments or drop me a message on Discord (AleskaArt#1058 ) Will be more than happy to answer!