I made one EEZybotArm, designed by Carlo Franciscone. You can visit his website here: http://www.eezyrobots.it.

The STLFiles can be downloaded from Thingiverse: https://www.thingiverse.com/thing:283....

As mentioned in the video:

Types of stepper motors: https://learn.adafruit.com/allabout...
Convert the unipolar motor into a bipolar one: https://coeleveld.com/wpcontent/uplo...
Arduino Uno: https://store.arduino.cc/arduinouno...
A source for the stepper motors: https://www.amazon.de/ANGEEK28BYJ48...
Step stepper driver shield: https://www.amazon.de/gp/product/B07D...