There are a few ways to create custom shapes in Illustrator. The first way is to use the Shape tool. The Shape tool can be used to create any type of shape, including circles, rectangles, and triangles. The second way is to use the Polygonal tool. The Polygonal tool can be used to create any type of polygonal shape, including squares, rectangles, and triangles. The last way is to use the Pathfinder tool. The Pathfinder tool can be used to create any type of path or design, including curves and arcs.