Wrinkle tool / brush in Illustrator and how to use it tutorial in CC 2017 2015 CS6 CS5 etc to deform paths
You can find the wrinkle tool in the width tool section of the Illustrator toolbar. The wrinkle tool can be used with paths, closed and open, strokes, lines, type and much more. You can double click the wrinkle tool icon in the toolbar to display the options to be applied to the selected path.
There are a lot of options to take in with the wrinkle tool such as
brush affects anchor
brush affects anchor in tangent
brush affects anchor out tangent
There is a lot of randomness with the wrinkle tool in Illustrator so if the setting is set to 100% you probably won't get 100% but perhaps something close (be nice if it was more like the brush tools with a range of settings and not just a setting
On the right, most of the settings have been set to emphasis vertical so you can see no wrinkling on the horizontal.
Anyway, just select the paths and then apply the wrinkle tool to the paths (or path) and the wrinkles will be added but the key thing to remember is that in many cases, a lot of points will be added especially if you set the complexity (great for a scribble like effect with the wrinkle tool especially mixed with angle) and also detail (great for just adding a lot of points especially to a localized area if you set the wrinkle settings low or zero and set a small brush size for the localized area (or the entire set of paths if you have a large brush size for the wrinkle tool)
Anyway, the wrinkle tool allows for you to add the effect either vertically or horizontal or a little in one direction and a lot in another (again, this is random for creating some interesting curved and wrinkled designs - odd that there appears to be no corner and smooth feature with this tool). You can also control the overall intensity of the brush effect via the size as well as intensity, for serious settings set it to 100% (but sadly no more, what is it with Illustrator that the settings rarely can go to 1000%) and if you wish to create only a subtle change with perhaps multiple re-applies then use a low setting of intensity and wrinkle option vertical and horizontal.
If you want to use it just for adding points then set the wrinkle to 0 and set the complexity and detail to a little higher (5 and 2 etc to add a lot of points and complexity). The wrinkle tool does need the settings to be all set correctly for it to work so you may find that if you have no horizontal setting and all the lines are vertical then nothing much will happen.
The image on the left shows a lot of points (but no wrinkling) and they have been then moved using the direct selection tool by selecting the individual points and then dragging them
Another great feature of the wrinkle setting in Illustrator is that you can modify the anchor and tangent or anchor or tangent and so you can keep the lines or paths in the same place but the shape will radically change but all the anchors will be stuck in the same location. Likewise, the tangent can be set to off and the anchors can be made to move.
You can also use the wrinkle tool / wrinkle brush setting 'angle' to change the angle of the anchors etc as well as the tangents (depending on the settings) to create lines going off approximately in 60 degrees or 30 degrees etc depending on the setting. Sometimes randomness in the angle kicks in and sometimes not. Again, I would love to see randomness with a little more control to the range of randomness also as well settings to the negative as well as just positive.
The wrinkle tool can modify Illustrator paths (closed or open) in many extreme ways to create some truly unusual shapes even from a basic path such as a circle or square and can also be used to wrinkle converted type as well as expanded symbols. It is much like the tweak filter but it comes with many additional features and it can be used like a transform tool as well. A very useful feature tucked away in the width tool section of the toolbar
The image on the right used the angle set to 60 degrees and horizontal set to 100% and vertical 0% and brush affects anchor points only - the wrinkle then generates an intense angled brush work with a basic path (in this case, a square)
You can find many other tutorials on Illustrator such as
and many others