Select a shape or create one using the tools such as rectangle as well as pen tool etc. Apply the effect
Window menu and Astute Graphics and
Generates paths around the edge of the selected shape or shapes and that can be a rectangle but it can also be other designs such as live type
Includes density, size, throw, spread, angle, curvature, shape, positioning, style, color, opacity, seed etc as well as few features to detach and remove via the right side menu
If set low then you get very few additional paths, set high, you will get a lots of extra paths. Probably best at about 1000%
Make very big designs if you increase the size, very small tiny paths if the value is set small.
Low, keeps the paths close to the object. High, throws them off the object and not touching the object.
Works more around the object itself
Controls the angle, the randomness of the angle.
If you have it low, more round; if the value is high, a sharper shape is generated
More like the order, by default on top but you can also have the object deleted and also the option for below the vector as well.
You can use the original coloring, the shape's color or you can have a specified color and also you can have a specified opacity (not certain about this as you can set the opacity in the control bar). There appears to be no element of randomness here but if you want that you can go to the Randomino and use that to create all kinds of variant colors and opacity etc
Randomino,, Youtube video on subject
Randomizes the result.
At the side of most of the controls (right side) there is a limited set of distribution profiles, uniform or more to one end etc, worth trying out to change the strength of the density, angle etc
It is a live effect so you can close the panel and work on something else and then come back to it and double click the entry in the appearance panel and continue to work on it. You can also add other live effects to it such as drop shadows and transforms
You can also expand everything via the object menu and expand appearance and then work on the individual paths such as re-color them or shift them or use them with transform each etc.
You can use it with the repeat feature but it should be noted it does create a lot of paths Youtube video on subject
You can also go to the pathfinder panel and use the unite etc feature to combine all the spots and dots into a single path which can then also be modified by the tool itself to add even more amazing dots. Youtube video on subject