Plotting the render layer?

Hello, do you know a way of how to make the render layer actually draw on itself? I have a white dot in my scene and when I move it around I want it to draw on the layer.

Any ideas?

(I tried vector blur but it does not work).

there’s a new tool the name of which i can’t recall. i think it might be ‘dynamic paint’. so you would designate one mesh as a ‘brush’ and another as a ‘canvas’ and you animate the brush, and it leaves a visible trail, just like a real brush would.