I made my own robotic arm, it works with arduino uno and 5 servomotor of 10 kg and a mini servo, you can print it and if you want I send you my code.
you must print all the pieces,
it works good and is a good project for school.
print it with a density of 30 % in order to be light.
I'm a studen at udlap and I make designs just for fun, but I'm serious when I say that I love design, but sometimes i just dont have the time or the inspiration.