The spray paint tool allows you to draw on the screen and produce a splattered, spray can inspired stroke. The current Stroke Color will be the color of the drawn path. The opacity option lets you make the brush stroke appear transparent.

The Brush Size option allows you to specify how wide of a stroke is drawn.

The Smoothing option allows you to control how much automatic smoothing is applied to any paths drawn. Maximum smoothing will remove many points in an attempt to make a very smooth curve (at the expense of accuracy). Minimum smoothing will leave all points in the path, preserving accuracy (what you draw is what you get).

The widget for spray paint elements also allows you to modify the shape of the stroke after you have completed it.