You can create many dynamic three dimensions sketches with only one perspective point. For example, here I am explaining you how to create a human figure in 3-D.
Step 1: Near the bottom of the page, draw a small point (your perspective point). For the top of the torso cube, draw a trapezoid. Keep this thing in mind that the top line should be longer than the bottom line and the side lines should extend all the way down to the point. Between the top of trapezoid and the perspective point, draw a horizontal line about halfway. This will act as the waist line and divide the torso from the legs. Between the point and the waist line, draw another horizontal line halfway. It will help you mark the bottom of the legs.
Step 2: On top of the torso cube, add an oval for the head. On the sides of the torso for the shoulders, add two small curves lines. On each side extends, add a diagonal line from the shoulder to the perspective point. It will mark out the arms. Inside the arms, add two curved lines. Just below the waist, place these lines. It will help you mark out the hands.
Step 3: Draw a curved line from the center back of the head and curves down, across the center of the face. And across the middle of the face, add a horizontal curved line. These lines will mark out the details of the face. To the right-hand side of the head, add a diagonal line. To the torso, this line should connect and will act as a neck guideline. Add a ring around the shoulders, waist and neck for the character’s ringer T-shirt. At the bottom of the legs, add two small ovals for the feet.
Step 4: On the middle right-hand side of the head, draw a small circle for the ear. On the horizontal face, add two ovals guideline for the eyes. Just above the eyes, add two eyebrows with curved lines. With a small triangle, add the nose between the chin and the eyes. With a small curved line, add the mouth between the chin and the nose. On top of the head, you can create the hair with a large downward-facing “C” shape. With small triangular-shaped curves, add locks of hair.
Step 5: Remove all the guidelines properly and ink the whole illustration. Now, let the ink dry and then erase your pencil line.
I hope this is one of the simplest ways to draw 3D Sketches.