Playing with Knives! Fun with the Knife Tool in Adobe Illustrator

A frequently overlooked tool in Adobe Illustrator is the Knife Tool. Its main function is to cut objects into parts. I want to show you several ways we can make the Knife Tool more exciting and fun to use.

Cutting an object into pieces

You might draw the shape of a tree and have just one continuous shape. It may end up looking more like broccoli than a tree. To correct that, you could take the Knife Tool and drag from one side to the other to divide the shape into the leaves and trunk. Now you can change the colors appropriately – and even add some small details.

Cutting an object into a couple of pieces is useful when the need arises, however the truth is there are other ways to do the same thing, so often the Knife Tool is shunned. I want to show you several ways we can use the Knife Tool to create cutting edge designs.

Note:

Before we get too far along, it is important to note there are two sharp objects in Illustrator: The Knife Tool, located hidden under the Eraser Tool, and the Slice Tool which is found right above the Fill and Stroke icons. The Slice Tool has more to do with prepping work for the web and not what we want for these exercises, so let’s look at some ways to make using the Knife Tool more interesting!

Rando-Mosaic

(Note: Knife Tool works best by starting outside the square and ending outside the square – that way you make sure and cross all the edges.)

I remember doing this as a kid with colored pencils and construction paper. As the name implies it is a randomly created mosaic beginning with a white square and cut up with the Knife Tool. This might be the simplest of simple things to do with the Knife Tool. To add the color, simply select each area and add a Fill, or to give more interest use patterns, gradients or even color themes.

Broken Mirror

Begin with an oval filled with the default swatch Super Soft Black Vignette (or any dark to transparent radial gradient.)

Using the Knife Tool cut through from side to side and watch how the gradient behaves. It multiplies the vignettes and with some imagination can become a broken mirror!

(Note, be sure and lock the layer with the frame so you won’t cut it as well)

Designer Briefcase

Begin with a rounded rectangle, duplicate it. Select the back one, slide slightly to one side and color it gray. Add a handle for looks! Select only the top layer and using the Knife Tool design away. Holding the ALT-Shift (PC) or Option-Shift (Mac) will let you create straight or diagonal lines as in the middle example.

Or perhaps you want to customize a Zebra or Horse!


As mentioned above, some options for adding color are to simply use the selection tools and Fill to add color. This is easy enough when there are only a few areas. But if it is more complex using the Live Paint Bucket Tool may be the best choice. Select it all, and then click on a desired area with the Live Paint Bucket Tool. It should highlight the individual areas with a default red outline.


Adobe provides a small triple color preview box along with the Live Paint Bucket Tool. This allows you to quickly change colors by using the arrow keys to navigate through the Swatches showing you the previous, current, and upcoming colors.


Note: If you decide to use colors from the libraries, for instance a collection of gradients, and want to be able to scroll through them using the arrow keys simply select the colors and add to the Swatches Panel.

Create-a Scape

One other way to have some fun with the Knife Tool is to begin with an 8 x 10 inch rectangle and drag the Knife Tool through to create a Landscape, Cityscape, Back-scape, or Underwater-scape. Any kind of scenery you want to create. Using the radial gradient (here it is Sky 21) on the sky area and dragging the gradient upwards will give a great setting or rising sun. Small marks with the Knife Tool adds movement to the brook or create distant birds in the air.

Here are some other ideas for Create-a-Scapes!

Hint: When interior shapes are made with the Knife Tool it is best to zoom in close so you can make sure you are closing your paths. If you can’t select a single interior shape after you have cut it – say a fish – from the background area (water) you probably didn’t end where you started with the Knife Tool. Just undo and try again.

Summary

So there you have it, some fun ways of “Playing with Knives” when using the Knife Tool in Adobe Illustrator. Have fun and come up with even more ideas to use the Knife Tool.
For your convenience, I have added links to the Mirror, Briefcase, Horse and Zebra used in the illustrations. Any other illustrations or ideas start with a simple rectangle.

Mirror
Briefcase
Zebra
Horse

For more information, check out my website at denawilson.net and my book, “LEARN Adobe Illustrator CC, for Graphic Design and Illustration!” by Wilson, Lourekas, and Schwartz.