Learn about reference geometry, including planes, points, and curves. Create planes based on existing planes or model geometry. Create points, axes, and coordinate systems to aid in the creation of features and helps with the use of measurement tools. Project a sketch onto a sketch or face to create a 3D curve. Create 2D or 3D sketches where faces of a model intersect. Create a curve through a set of X, Y, and Z locations relative to the origin. Create a curve defined by a mathematical equation. Model a spring using a variable pitch helix as the path for a sweep.