Magic Pen Inductive Tank - Magic Tank ::INFPASS

Just use the marker and draw a line on paper, then set the tank on the
line and it follows the line! Amazing is’t it? The tanks have an optical
sensor that reads the black line drawn on a piece of paper. Simply draw
a thick line that is at least a 0.3 inch thickness, place the tank on
the drawn line and it will run on the line automatically. Put as many of
these toy tanks on the track and they will not interfere with each
other.