1. A portable writing apparatus, comprising: a writing instrument carriage shaped to removably hold a writing instrument and change between types of the writing instrument; an actuator system coupled to the writing instrument carriage to move the writing instrument carriage; a pressure sensor system coupled to measure a pressure applied by the writing instrument; and a controller electrically coupled to the actuator system and the pressure sensor system, wherein the controller includes logic that when executed by the controller causes the controller to perform operations including: receiving input data describing a user's handwritten characters; controlling the actuator system to move the writing instrument carriage in response to the input data, wherein the writing instrument carriage recreates a shape of the user's handwritten characters; and measuring the pressure applied by the writing instrument while the writing instrument carriage recreates a shape of the user's handwritten characters; and adjusting the pressure applied by the actuator system.