I do get a few requests for process/walkthroughs; normally I just paint on a single layer, or if I do use a few I constantly flatten and forget to do screencaps along the way. I ended working on GvS in all its 70-something layers of lulz to make this.
I suppose it counts as a tutorial, but I'm really not trying to teach anything. If anything, this ought to be a deterrent! I'm a clumsy painter and I'm sure none of you want to go through such a convoluted process.
As for tools: Just a brush and eraser. No filters, no smudge/blur etc.