I built my first robotic arm when I was fifteen. It was a hydraulic 5dof
plus gripper robot arm. At that time, as I had little money of my own and I didn't had
access to materials I needed, I had to improvise a lot. Instead of the hydraulic cylinders,
to action the arm's segments and the gripper, I used syringes and I used car windscreen washer
pumps to action them. The get feedback position on them I transformed them into rheostats by
making a resistance wire wound around the cylinder and add a cursor on piston. At last there
was a fairly primitive interface mainly based on solid-state relays, which was meant to interface
with a z80 computer.
I got it working partially in the end, as I was still missing a few components. Few years latter (when I was a student) I decided to transform it into a lamp. The picture in the right is what is left of it after all this years - a modelled hand with a bone which was part of the lamp I created, inside which the gripper of my old robotic arm rests in peace.