ScisDrawing and editing paths
Shortcuts are written in their macOS form. On Windows, read ⌘ as Ctrl, ⌥ as Alt and ⇧ as Shift.
The pen tool
The Pen tool (P) builds a path point by point. Click to drop a corner anchor; press and drag instead and the anchor keeps handles, so the path leaves it as a curve. Hold ⇧ while you drag to hold the handle to 45° steps, and hold ⌥ to move only the outgoing handle, which turns the anchor into a corner and frees the next segment from the last one.
While a path is open the tool changes as you move over it. Over the first anchor it closes the path, over a segment it adds an anchor, and over an existing anchor it removes one. With no path in progress, moving over the loose end of an open path picks that path up so you carry on drawing from it. Enter or Esc ends the path and leaves it open; Delete removes the anchor you last placed. Enter or Esc ends the path and leaves it open; Delete removes the anchor you last placed.
The same slot holds Add Anchor Point (+), Delete Anchor Point (−) and the Anchor Point tool (⇧C). With the Anchor Point tool, drag from a corner anchor to pull out a matched pair of handles, or drag a single handle to break the pair so the two sides move apart.
The curvature tool
The Curvature tool (⇧~) fits a smooth curve through the points you click, with a preview running to the pointer as you go. ⌥-click to drop a corner point rather than a smooth one, and double-click any point to switch it between the two. Drag a point to move it and the curve refits. Click the first point to close the shape, or press Enter to finish. Delete removes the last point and Esc abandons the path.
Anchors, handles and the Direct Selection tool
The Direct Selection tool (A) works on the parts of a path. Click an anchor to select it, ⇧-click to add or remove one, or drag a marquee over empty space to catch every anchor inside it. Dragging selected anchors moves them; ⇧ restricts the move to 45° steps.
Drag a handle to change the curve on its side. Handles that belong to a smooth anchor move together, so the curve stays continuous; hold ⌥ as you drag to break that link and steer one side alone, and ⇧ to hold the handle to an angle. You can also drag a segment itself: a curved segment bends under the pointer, and a straight one carries both of its anchors along.
The Group Selection tool shares this slot and picks whole objects out of a group rather than anchors.
Live shapes and their widgets
Rectangles, rounded rectangles, ellipses and polygons stay live: they keep their parameters and rebuild their path whenever you change one. While you drag a shape out, ⇧ makes it regular and ⌥ draws it from the centre. The arrow keys work during the drag too - up and right add, down and left subtract - changing the sides of a polygon, the points of a star, or the corner radius of a rounded rectangle.
Select a single live shape and small round handles appear just inside its corners; they are hidden when the shape is too small on screen to show them clearly. Drag one with the Selection tool (V) to round all the corners at once, or with Direct Selection to round only the corner you are holding. ⌥-click a corner handle to step it through round, inverted and chamfer - again all four corners with the Selection tool, one corner with Direct Selection.
An ellipse shows a square handle instead: one on a whole ellipse, and one at each end of the pie once you have opened one. Drag one to open a wedge out of the shape, with ⇧ snapping the angle to 15° steps; bringing the end back round to the start restores the whole ellipse. The Properties panel holds the same values as numbers: radius and corner type, per-corner radii, polygon sides, and pie start and end in degrees.
Shape builder and pathfinder
The Shape Builder tool (⇧M) works on two or more selected paths. It divides their overlaps into regions and highlights whichever one the pointer is over; drag a line across several regions to merge them into one object, which takes the appearance of the shape it came from, or ⌥-drag across them to delete them.
The Pathfinder panel (⇧⌘F9) does the same work as commands. The shape modes are Unite, Minus Front, Intersect and Exclude; below them sit Divide, Trim, Merge, Crop, Minus Back and Outline. The results keep curves rather than flattening them to line segments. Effect › Pathfinder applies Add, Intersect, Exclude, Subtract and Minus Back as live effects instead, leaving the original objects intact.
Object › Path gathers the rest: Join (⌘J), Average (⌥⌘J), Outline Stroke, Offset Path, Reverse Path Direction, Simplify, Add and Remove Anchor Points, Split Into Grid and Clean Up.
Compound paths and clipping masks
Object › Compound Path › Make (⌘8) folds the selected paths into one object filled by the even-odd rule, so an inner contour cuts a hole through the one around it. The result takes the appearance of the lowest object in the selection. Release (⌥⇧⌘8) gives each contour back as a path of its own.
Object › Clipping Mask › Make (⌘7) uses the topmost selected object, which must be a path, to clip everything below it. Scissor puts them all into a clipping group and clears the mask path's own fill and stroke. Release (⌥⌘7) turns the clipping group back into an ordinary group, so nothing is clipped any more and every object, the mask path included, stays where it was. Make Opacity Mask in the same submenu masks by tone rather than by outline.
Smart guides and snapping
Smart guides (View › Smart Guides, ⌘U) watch the visible artwork and the boards as you draw or drag. What you are moving snaps to the edges, centres and anchors of its neighbours, and a line appears back to whatever it lined up with, labelled with the kind of match - anchor, center, corner or align.
Two further guides appear on their own. When the object you are moving would sit at the same distance from its neighbours as they sit from each other, it snaps there and the two equal gaps are drawn with the measurement shown; this works both for continuing a run of evenly spaced objects and for centring one in the gap between two. And when you drag away from a starting point, the direction snaps onto a construction line every 45° from the constrain angle, drawn as a long line with the angle beside it.
Snap to Point (⌥⌘') and Snap to Grid (⇧⌘') are separate switches in the View menu. With Snap to Grid on, everything lands on the grid subdivision and the smart guides stand aside.