A pen has a marking device operative to mark a visible path onto a surface. The marking device is electronically controllable to change at least one of the attributes of the path. The attributes are constituted by the characteristics of the ink being deposited and can include the amount of ink deposited, the width of the line produced, and the color of the ink deposited. The pen also includes a user interface provided by one or more potentiometers or control buttons such that the user may modify the attributes. Additionally, the pen may include a display to indicate the selected attributes to the user and a sensing device for sensing coded data.