I worked on building a mechanical arm with Lego today.
This is the arm in it's open form.
This is it closing up.
If I disconnect the bottom, it becomes a shorter tool.
It takes a while to fix if it breaks. It has to be adjusted exactly the same on both sides until it's working properly. In this photo, I'm adjusting it so that it will become curved, as you can see in the next photo:
This can be useful reaching something high up on a shelf, or on the top of the fridge, like today when I reached my mom's camera. (She's just finding this out now. She seems a little surprised and unimpressed.)
The mechanical arm can also be useful in reaching for random objects, as long as they're not too heavy;
in touching food that you don't really like;
and in reaching small snacks that you do like to eat.
I might make a few adjustments to the arm, and make it look better.