Easy marbled pattern tutorial (which is actually just a technique I made up after playing around with random tools).
I use IbisPaint so some tools might be different for your program.
Start with drawing some lines in different colours. They don't need to be perfectly even, actually a bit of randomness is better - I used a watercolour brush here. Use colours from a palette if you're not sure what colours fit well together.
Apply some distortions/transformations. Use as many as you like to get the effect you want. I used a twirl and then a wave.
The wave creates white spaces, so I needed to zoom in to get rid of them.
If you aren't happy with any part of the picture, you can manually paint over it at this point. I used the smudge tool so that it's not so pronounced where I edited it.
Yay! Congrats! Pretty paint swirls achieved!














