Found in the Mesh Edit sub-tab of the Modeling toolbox, the Slice tool sets a slicing plane through the currently-selected geometry. The slice plane is interactively set by dragging out the tool across a 3D Viewport. The first click in the 3D view sets the Start position for the slice. Clicking and dragging extends the slicing plane out to the End position, which can also be dragged interactively. The orientation of the plane is relative to the Work Plane, drawing perpendicular to its current position. The Start and End positions are simply X,Y, and Z positions that are set with the mouse, or numerically on the Tool Properties panel.
As long as the tool is active, you can drag the cutting plane by clicking on either of the blue end handles, or clicking and dragging anywhere along the pink line that connects the start and end points. To create a new slice using the same basic length and axis, but set a new center position, you can middle-click at the new location. The slice plane jumps up to that location and create a new slice. To begin a completely new slice, use the Shift+click and drag shortcut. This leaves the previous slice in place and begins a reset slice action at the mouse down position.
The following Slice options are available for Slice:
• Start X/Y/Z - determines the beginning position that defines the slicing plane. You can edit the position interactively in the viewport, or accurately define values with the XYZ coordinate inputs.
• End X/Y/Z - determines the ending position that defines the slicing plane. You can edit the position interactively in the viewport, or accurately define values with the XYZ coordinate inputs.
• Fast Slice - when this option is enabled, the slicing action won't occur, as the plane is edited until the mouse button is released. This can help to increase performance when slicing dense meshes.
• Angle Snap - when snapping is enabled (press the X key to temporarily toggle snapping states), the slicing plane snaps (jumps) to the nearest specified angle.
• Angle - determines the snapping angle for Angle Snap in degrees of rotation.
• Split - slices the surface into distinct separated surfaces on either side of the slice line.
• Cap Sections - with the Split option enabled, the Cap option adds a polygon cap to the separated objects, where there are enclosed volumes.
• Gap - with the Split option enabled, the Gap option increases the thickness of the cutting plane, eliminating a larger portion of the target surface.
• Infinite - with the Infinite option enabled, the defined line section is extended indefinitely beyond the Start and End values.