For the group assignment you can click on this link Group assignment week 15.
For designing the penholder i used tinkercad.I also search for designs on thingiverse to get a idea and the idea is that it has to work with a servo motor to get it up and down when drawing.
For the design and making of the stepper driver you can see in on my week 12 assignment page.Here is the link to Week 12 assignment.