The symbol stipplism plugin tool is from Astute Graphics and is for Illustrator and is the second part of the set and is great for manipulating symbols and paths in 1000s of ways such as creating halftone effects, random scatter and much more.
You can find it via the Effects menu and Stipplism.
Select a normal path for the tool to work. In the panel, select a preset to use and set density and overall scale and click OK. It uses any presets you currently have. It is a live effect, you can modify it at any point and go back to the settings by selecting the artwork and then clicking on the entry in the appearance panel (which can be found in the window menu)
You can use anything as a preset, so type, brush strokes, multiple paths, images, compound paths etc, all can be used with this tool just by converting them into a preset.
You can see the dialog when you select a path or paths and go to the effects menu and Stipplism. The dialog comes with a large number of options such as a seed (which randomizes the whole thing but usefully you can store the random seed and return it via the store and recall as well as skip through the various stored random seeds which is very useful).
The density controls how many or how few of the objects that are generated within the space of the selected path. There is also a quality section which reduces or increases the quality of the generated result but I have not noticed much difference (it is subtle). Actually the quality is probably my least used slider in the plugin. I am certain that many others will find the quality slider of a lot of use.
You have a dot section but you can select the required preset from a list which sadly is not visual so you better name your shapes / presets in a sensible manner.
There is a variants feature which is useful but that requires you to use a naming convention for the presets and that can be found on the Astute website as there are many interesting features you can add simply by naming them in different ways but it is a fairly obscure language setup.
You can change the overall scale of the selected preset though you could do that at the actual creation of the preset as well as setting the angle / rotation. Set to 2 to create large as well as very small designs. You can also vary the scale and rotation which is useful so you can make all the presets between twice the size and the actual size (not totally flexible. if you wish to have them range between 1/2 and 2 but I guess you can set the item up and then scale between 1 and 4 instead to get the same ratio). You can set the rotation to follow the path which is quite useful to create interesting frames etc.
You can colorize the presets as well based on the color of the selected object or to an actual color (though sadly not randomized). You can also preview the result which is quite useful.
There is an option to use the registration point and that appears at first to have no use but you can change the result of the plugin by editing the symbol's registration point (you can see that when you edit the preset and move the object away from the center of the initial position). Changing the registration radically re-positions the artwork if the artwork is still live.
You could use the default setup of the panel but if you want to create some interesting artwork then create your own presets (or obtain some from this site). You can add really basic shapes to the panel such as a line or perhaps an image or perhaps use multiple colorful lines or perhaps circles or triangles and even with very basic shapes you can create all kinds of interesting artwork but you can also add very complex artwork to the presets panel as well and then use that with the plugin tool. The key thing is to setup the panel in the best way for the best results for the tool and that is a clean (without the default items) and well named set as the drop down of the presets does not display the image of the preset so you have only the name to go by.
To use, you can select multiple objects and then use the effect. To work, you must have at least one preset to be able to select from the symbols list. Set the preview to be on otherwise you will see nothing but if you have a complex imagery then perhaps it is best to leave the preview off. Once you have finished, click OK and then to use the item as a set of actual paths that can be used in AI, use the object menu and expand appearance and then expand command. You can also use the artworks as live effects and you can modify the result via the appearance panel. If you select the artwork, go to the appearance panel and you will see the line. You can edit the effect by clicking on that line. You can also add additional fills and strokes to the artwork but do this, move the line to the fill or move it to the stroke section on the appearance panel.
You can use the effect with the fill and fill a path with lots of presets or you can select a stroke or the stroke of a path and then use the tool with that instead of the fill. You can add the effect multiple times to multiple strokes attached to a path. You can also combine the effect with width profiles as well for the stroke as well as using the dash options so you can get a pile of presets in one section and then a gap and then some more presets and so on.
You can select an image and use the plugin with that so you can turn any image into a vector made up of lines or dots or triangles or rings or etc any kind of item that can be stored as a preset. You can add all the other options such as varying the size of the preset as well as rotation as well as changing the density and the higher and better the quality, the better the image will look. You can then again expand the result and appearance. If you wish to combine the image and the effect then the only way would be to duplicate the original artwork and add the effect to the duplicated result. You can then blend the image and the vector using blending modes.
You can select type (live type) and then use that with the presets and the effect. You can use all the same tools such as rotation and random rotation and density and scaling etc. You can also add into the mix all the other effects as well via the appearance panel and other fills etc. You can also use type as a preset and then add the same type or different type to the currently selected text. All number of combinations of text and text can be generated and expanded though the more complex the text, the slower the render of the final result. You can have a whole page of text as a preset and then use that in the effect.
You can edit the effect at any point. Select the object and then go to the appearance panel and click the entry and the panel will reappear and you can edit the settings. You can also move the settings from one entry to another such as move it to another fill or duplicate the associated fill or just apply the effect to the stroke or combine the effect with others such as distort and transform and zigzag and blur etc.
Related to this but not using presets and limited to circles. Still, the limitation means you have to look at how you can use those circles in many different ways as well as combining the result with other features of the application and set such as Randomino to randomly color as well as scale and rotate etc the design. With Randomino https://youtu.be/pv7dF2_2SSk