Below is one of the link of the turtle robot video from youtube.
To know more about Turtle robot read this micro blog.
So how about building your own Turtle Robot (Hardware) right from scratch, which involves designing and building of chassis, figuring out type of motors (DC, Stepper, Servo etc) to be used, computing board (Arduino/Raspberry pi) to be select, type of wheels to use , designing pen mechanism and providing connectivity (wired/wireless) to the computer.
And also the coding interface (Scratch/Snap4Arduino/TurtleLogo etc) to make your robot to follow the commands and draw different shapes.
Can you construct and code a Turtle Robot which can draw a sine wave on a sheet of paper. And what other complex shapes or arts can it draw.
Report your work done and achievements through pictures, messages and videos.
While you are making whatever questions you have, whenever you need help, do not hesitate to ask by replying to this topic.
Some References to know more about how to get things done