Explore the fourth installment in a series on constructing an affordable 3D-printed robot arm using Arduino. Learn how to complete the hardware build by assembling axis 2 and axis 1. Discover the process of installing motors, bearings, and other components. Access all necessary files for the build through the provided GitHub link. Look forward to the next video, which will cover connecting stepper motors to the electronics and making the arm move. Support the creator's future projects through subscriptions, donations, or Patreon.