Machine Design involves application of engineering fundamentals to the design of machine components. The field of machine design is a huge and growing field, and requires life-long learning to stay abreast in this field. Some resources for MAE3 are:
Fundamentals
General Design Resources
507 Mechanical Movements (an excellent resource when you need some inspiration for a way to properly drive some component of your robot)
Good Design Practices
Strain Relief for electrical wiring.
Additional Design Resources
MAE Design Resources Page (has a wide range of links to resources all over the web)