You can find the tool in the tools panel, you can also find the panel via the window menu and Astute Graphics.
It is part of the plugins suite from Astute Graphics for PC and Mac
It works with paths, live shapes etc and creates a contour / offset effect in all kinds of subtle and dramatic ways.
Select a circle / ellipse etc (or any other) and go to the panel. To start, you need to click the apply button which is at the bottom of the panel. The key thing is to set the distance to use so set it to 200 or so and then also decide whether each step is applied to that distance or the entire set (or total) is for that value. You can use this with fills and strokes. The next key thing for this panel is the steps setting and that needs to be more than 1 so set it to 10 or 20 and you will see multiple copies of your design reaching outwards from the vector (live) and clicking the offset outwards / inwards at the top right, you can great multiple designs going off from that source path.
You can use it with a fill or stroke, if it has no fill or stroke, those settings won't make any difference. If there is a fill then set fill to retain / remove / alter color etc and if using something valid then use blend original to black / blue etc or use a gradient. You also do exactly the same for the stroke and also bring in a change to the stroke width as that can be changed based on what it is and your setting.
You can also fade the paths by using the opacity setting, if 100% then nothing changes.
Select some type or create some and then set the fill to nil via the fill in the top left and set a stroke for the type and stroke weight. Go to the panel and then click the apply button at the the bottom of the panel to add your stroke contour design. You can then modify the number of steps to 10 or 12 and also set the distance to 200pt and set to total, so you will end up with your 10 or so strokes added within the confines of the 200pt. Set the corner type to rounded. Set the stroke to alter weight and set a weight so if you have an initial setting of 1pt for your type and the setting of 3pt, the generated lines will increase from 1pt to 3pt. You can also alter the color so if you start with black say and then set the alteration color to green then by selecting blend original to you will go from black to green. You can also select a gradient preset via the drop down and 'pick from'. You can also set the opacity to be altered by checking the alter opacity, you can have it fade away by setting it to 5% say. Once you have created your design, you can go to the object menu and expand appearance or you can go to the right side menu of the panel and select the detach command and you can then detach it from the type and continue to edit it using other features of the application.
You can re-color the generated artwork by using the Randomino (also from Astute Graphics). This will only work once you have expanded or detached the artwork. It can be used to re-color all the lines, fills etc as well as apply other effects such as scale and random rotation etc Youtube video on subject
You can use the tool with the repeat feature via the object menu in repeat radial. You can create the design and then apply the repeat or you can create a line (segment tool) and then apply the repeat and then double click the object and add the effect afterwards. You can modify the design such as rotate the object and scale or change the length of the line as well as add additional points or curves using curvature etc to create 1000s of amazing designs and they are all still live. You can continue to modify the angle of the repeat as well as the number of instance. To change the settings within the object and you can change the blend color or use a gradient as well as the number of steps and length as well as well as the weight and more.
Repeat, Youtube video on subject
Curvature, Youtube video on subject