Doing Form Studies So That You Can Rotate Objects And Figures In Three Dimensions
Introduction
Practicing drawing primitive forms like boxes, spheres, cylinders, and cones in any orientation is useful if you want to become good at drawing things in any orientation from your imagination. (3D models for primitive forms can be found here.)
These primitive forms can also be manipulated; they can be twisted, bent, squeezed, stretched, added, or subtracted from each other. Shapes can be traced along a line to create new forms. 3D models for organic forms can be found here , and models for combined forms here .
More on that below.
These simplified forms can be combined into more complex forms, creating real-world objects and figures. You can then start to draw the object rotated from imagination by rotating the simplified form representation of it.
Demonstration: Chess pawn broken down into simple forms an rotated.
You can practice this without any photo reference! It is fun to construct imaginary cartoon characters from primitive forms.
You can practice this using the 3D models on the Practice Drawing This website . These 3D models can be viewed online in most browsers, including ones on mobile phones.
Form studies are an excellent exercise for learning how to place things accurately in a three-dimensional space. It is way more fun to position these forms in a three-dimensional space without first working out a perspective grid, and it’s fun to do it by eye. For drawing, I prefer this over studying the math behind perspective. The drawing from memory exercise trains you to see when things are off. Combined with form studies, this will train you to place believable, perspective-correct forms in a three-dimensional space in any orientation.
You can use the forms in two ways:
1) Create more complex forms from simpler primitive forms, deformed or not. You can create imaginary constructions this way, but you can also look at photo references and, as an exercise, try to work out the underlying form of the thing in the picture. As starting points, these primitive forms can be used as approximations of more complex forms. After deforming the form, details can be added to it.
2) Another use is to be able to place objects in boxes. An exercise can be to draw boxes in several different orientations and then place an object or human in those boxes in their different orientations.
Form studies help practice placing things believably in a three-dimensional space and can help place details accurately.
The exercises mentioned in the Dexterity guide are useful precursors to doing form studies: they help you practice drawing straight lines, circles, and ellipses accurately and starting and stopping lines exactly at other lines, which is invaluable when drawing forms.
Primitive Forms
Start by practicing the primitive forms like boxes, spheres, cylinders, cones, and pyramids. They are the base building blocks and approximations of parts of the forms you see everywhere around you. (3D models for primitive forms can be found here.)
These primitive forms can be manipulated further to obtain better approximations.
Stretching And Squeezing
A form can be stretched and squeezed. Try to imagine that the forms have a fixed volume. When you stretch them, they become narrower in the middle, and when you squeeze them, they become fatter in the middle. (3D model for stretched/squeezed form can be found here.)
Twisting, Bending, And Wrapping
Boxes can be twisted: (3D model for twisted box can be found here.)
And longer forms like cylinders and long boxes can be bent: (3D model for bent cylinder.)
Forms can also be wrapped around other forms, which is a form of bending. (3D model for box wrapped around cylinder.)
Tracing Shapes Along A Path
A fun way to create forms is to draw a curved line and a shape at one side and trace that shape along the path created by the curved line. The shape can be a circle, a square, or any shape. 3d model of an ellipse traced along a path.)
Bending A Form Along a Path
You can also bend a cone or pyramid along a path. (3D model of cone bent along a path.)
Adding
Forms can be added to each other by studying interlocking forms: primitive forms that overlap each other in space, forming a new, combined form. (3D models of added forms.)
To find the intersecting line between the two forms, it is useful to draw many contour lines lightly on both forms to figure out where they touch.
The Bridgman anatomy illustrations make heavy use of interlocking (added) forms as this simplified arm demo shows. 
Subtracting
Similarly, forms can be subtracted from other forms. Parts can be cut away along a plane, or forms like boxes and cylinders can be cut out of other boxes and cylinders: (3D models of subtracted forms.)
Tips
Contour Lines
When drawing forms, it is useful to draw the contour lines on the forms—lines around the object that show how their surface bends in space. It helps you understand the underlying form.
Draw Through
Draw through the forms; draw the contour lines lightly on the back of the forms where you don’t see them. This helps you understand the form better and relate it to other objects better.
Also, draw the parts of forms hidden behind other forms to place them better relative to each other.
The Blob Method
The idea for the blob method comes from Proko: first, draw a blob-like form and then turn it into a primitive, like a box. Drawing a blob as an approximation of the final form first allows you to place the final form in the right place and proportions.
Accuracy
We’re talking about approximating complex forms using simplified forms. You don’t need to be deadly precise with the primitive and manipulated forms. Have fun with it!
Related Resources
Practice drawing the primitive and manipulated forms by using the 3D models on Practice Drawing This:
Then try to create simplified forms of reference images in the flashcards section:
