1. Sphere The sphere is the only shape which is the same 2D as it is 3D. This method starts by sketching a square and applying the Union Jack method to create a circle.
Sketching a sphere

2. Box/Crate Every shape in sketching, whether simple or complex starts with a crate.  This is used to ensure that when joining two or more shapes together the position and scale can be seen quickly.  The link below will take you to a video which shows the technique used to sketch a box or a crate which can then be used to help sketch another shape.
Sketching a box/crate

3. Pyramid Using the techniques learned previously, this video shows how to use a crate and convert it into a pyramid shape.
Sketching a pyramid

4. Cone To construct the cone we need to start with a crate, add a base to it and then apply what we learned in video 1: sketching a sphere. Using a combination of both of these methods, this video shows how to sketch a cone.
Sketching a cone