The present invention provides methods, processes, and systems for the manufacture of three-dimensional articles made of polymers using 3D printing. A layer of prepolymer is deposited on a build plate to form a powder bed. The deposited powder bed is heated to about 50° C. to about 170° C. Then, a solution of activating agent is printed on the powder bed in a predetermined pattern, and a stimulus is applied converting the prepolymer to the final polymer. After a predetermined period of time, sequential layers are printed to provide the three-dimensional article. The three-dimensional object can be cured to produce the three-dimensional article composed of the final polymers.