Blend. How to use the blend tool to combine objects (paths) in Illustrator CC 2019 2018 2017 2015 CS6 CS5 etc ? To blend between paths / objects, create some paths or use existing paths. Go to the blend tool in the toolbar. Select paths (though not required). Click center points or segments or points of those paths to generate the blend between the paths.
Options / Settings. The blend has a number of settings such as spacing (smooth color, specified steps etc) as well as settings related to each spacing method. Double click the icon in the toolbar to modify the settings. Access the settings for the blend tool via the tool icon. You can set the spacing method + Set to specified steps + Set the number of steps + Set orientation (to path etc) + Set preview to ON. Double click the blend icon in the toolbar. You can set the settings before you create the design or at any time afterwards for a particular combination as it is a live effect. You will see only a couple of settings such as smooth color and specified steps and the number of steps and specified distance and the distance as well as align to the page and align to the path. Personally, I generally use the number of steps with the blend tool but specified distance is great if you want to create a combination with paths added say every 10pt or 100pt or at any distance. The smooth color is probably the easiest but least useful (for me) tool but you can use it for create lovely highlights using multiple paths. Specified distance is probably my least used option but it is useful if you want to space the distance between each generated path to say 10pt or 40pt etc. The key thing to remember the result is always live and the settings can be changed at any time for the selected set of paths. The specified distance option is quite good for use if you want to distribute items so if you have one path at one side of the artboard and another path at the other side, you can then create paths 10pt or 20pt from path one to two etc.
Paths. You can combine standard paths, strokes, type and other objects in Illustrator. It is a live tool and modified at any point. The Illustrator blend tool smooths two or more paths into a group of intermediary paths. You don't have to use just two paths with the blend tool. You can combine multiple paths with the tool. They don't have to be the same type of paths either as the tool is very flexible and can mix and match many different paths though the results often are not what you would expect (such as paths flipped over etc). Create a number of paths (more than two) for the blend tool. Select the tool in the toolbar and then click on path 1 and then click on path 2 and follow that with clicks on other paths required and you will see the colors flow and shapes added from path 1 to 2 and 3 etc. I do not know if there is an internal limit to this. I guess there must be some upper limit.
Create spherical design. For example, create a blue circle and then a small white circle inside the blue circle. Click on the blue and white with the smooth option to create an instant highlight spherical design and as you can change the position of the start point for the inner circle you change the start position for the highlight. You can also simply just rotate the design around to change the angle of the highlight. You don't have to use two paths, you can use five or six etc colors so you can create a nice smooth path with blue and red and green and then white for the highlight (though it does not need to be white but just something lighter than the outside path).
Change color / points etc. You can also change the paths such as change the color and shape of the paths by using the blend in Illustrator. Once you have applied the effect, you can still alter the paths involved in the combination such as changing the shape of the paths or perhaps changing the color of the paths and that can be done by selecting the path using the direct selection tool and then changing the color or shape etc for that path or perhaps removing or adding points etc. Create a combination of paths using the blend tool. Go to the direct selection tool. Select the first or second etc path. Change the color via the toolbar fill color (or stroke). Go to the object menu and transform and rotate etc (to rotate one of the paths). Add a point to one of the paths by using the pen tool. Use the direct selection tool and manipulate the new point or others in the first path.
Spine. There is also a blend spine (not the paths used in the merge but the line connecting the paths) and you can also use the direct selection tool to select that spine and then shift the spine path and distort it from its default basic straight line. You can also then use tools such as curvature or use the anchor point to manipulate that spine by selecting the individual points of the spine or adding to the spine and then manipulating those. You can also use the menu commands found in the object / blend menu to replace the spine and this can be done by selecting the merged paths along with an additional path (open or closed) and the command will take the existing spine and replace it with the new path. You can change a spine such as straight line between two paths with a spine in a spiral etc You can also use closed paths to create some truly weird and wonderful abstract designs such as selecting the merged paths with a star and the result can be stunning (or just odd).
Type. You can use type with the blend tool as well. Click some text and then click some other text and you will see the paths are generated as well. The results can be varied. You can use it with all kinds of characters as well such as different numbers of characters and fonts and colors etc and it will merge them all with the generated paths (smooth or steps etc). You can also use two or more. You can change the spine. This is all still live so you can re-write the characters and you will see it change. You can go to the layers panel and see the structure of the generated path such as the spine and the supporting artwork. You can then click the little target button on the right of the entries to select.
Properties panel 2019 +. With CC 2019, once you have added your blends to the paths you can access the blend options via the properties panel.