A three-dimensional drawing device can include a housing configured for to be held in user's hand, shaped to allow manipulation of the housing like a pen, and configured to accept a strand of thermoplastic material. The drawing device has a nozzle assembly with an exit nozzle and a motor connected to a gear train that engages the strand such that rotation of the motor causes the feed stock to be extruded out of the exit nozzle to form a three-dimensional object. The motor can be controlled using a variable speed control mechanism or first and second actuators, thereby controlling movement of the strand, for example, to advance or retract the strand relative to the nozzle assembly.

A three-dimensional (3D) drawing pen can include a housing that has a port that permits insertion of a strand of material into the housing. The strand can be moved through the housing toward a nozzle assembly configured to permit the strand to be extruded out of the 3D drawing pen in a form that retains its shape against gravity in free space to draw a 3D object.

An apparatus comprising a three-dimensional (3D) drawing pen can permit a user to draw a 3D object in free space that retains its shape against gravity. The 3D drawing pen can include a body, a sensor supported by the body, a motor, and a nozzle assembly disposed at a distal end of the body. The motor can drive material toward the nozzle assembly upon actuation by the sensor. The nozzle assembly can include an extruder and an exit nozzle. The extruder can have a heating element for melting material and permitting the material to be extruded out of the exit nozzle in a solid form upon actuation of the motor by the sensor. The user can manipulate the 3D drawing pen to draw a 3D object that retains its shape against gravity.