I've searched high and low for an easy way to do this, but of course it turns out most people want to remove gradient banding 
I know usually people need to get rid of gradient banding, but I actually need to create it.
So, what is the easiest way to create gradient banding?
I know that you can do this in the gradient editor itself, by layering multiple color points on top of each other, but the tools are extremely flakey and it can be difficult/frustrating to do it this way. Especially if you already have a smooth gradient and want to introduce banding to it. What I want to know is; does anyone have any tips for using the editor to introduce banding to an already smooth gradient, within the gradient editor itself?
And failing that, is there a filter or some other method for introducing banding to a gradient that has already been applied to the image?

I know usually people need to get rid of gradient banding, but I actually need to create it.
So, what is the easiest way to create gradient banding?
I know that you can do this in the gradient editor itself, by layering multiple color points on top of each other, but the tools are extremely flakey and it can be difficult/frustrating to do it this way. Especially if you already have a smooth gradient and want to introduce banding to it. What I want to know is; does anyone have any tips for using the editor to introduce banding to an already smooth gradient, within the gradient editor itself?
And failing that, is there a filter or some other method for introducing banding to a gradient that has already been applied to the image?