https://www.dfrobot.com/product-823.html
This encoder is matched with 2wd miniQ Robot chassis. AB two-phase pulse wave,measured by two infrared reflective sensor.
robot chassisminiqencoderdfrobot
https://makezine.com/projects/designing-a-robot-chassis/
We will be using freely available tools like Google SketchUp to design and finally fabricate a chassis for a robot.
robot chassisdesigningmake