You can create a sharp, clean edge for a colored area using the Hard Mask tool, often combined with Precision's Shape Guides.
First, create your color block. You can do this by coloring an area with a brush, or by using the Filled Stroke tool with a shape from the Object Library.
Masking the Color Block
- On the same layer as your color block, select the Hard Mask tool from the Tool Wheel.
- Activate the Shape Guide you wish to use (e.g., Line, Rectangle) from the Precision menu. A guide will appear on your canvas.
- Position the guide to define the edge you want to create.
- Trace along the guide with the Hard Mask. This will erase everything from the current layer that falls under the mask's path.
- Turn off the Shape Guide and erase any other stray marks as needed.
- Pro Tip: To apply the same mask across multiple layers, use the Selection tool to select your mask stroke, duplicate it, and then move the copy to another layer.