Inkjet Printer Robot Wheels
Usually a robot uses 2 identical motors for drive in order to change directions or go straight.  Usually a printer will only have 1 motor to drive the paper and 1 motor to drive the print head.  And usually they are not identical.  Making it difficult to build a useful robot.  Also, printers usually use stepping motors.  Most people building their first (small) robot usually use continuous servo motors.  This makes for an easy to build first (small) robot as seen in this picture: