I am trying to build a lego claw arm to pick up stuff that is out of my reach and I need some ideas on how to design it. I would like a mechanism to be able to open and close the claw from the opposite end of the arm.

I'm not looking for an arm design which can extend. I would also like ideas about fixed-length arms. Also, I have many, many different TECHNIC pieces. Designs can be very complex and they can use large numbers of pieces.

3 Answers 3


If you're after a simple collapsible solution to reach those items just out of reach, you can start with the following setup:

Start of grabber

You can extend this for quite some way, and use longer bricks or beams throughout if you wish.

To finish it off, I'd use a couple of longer bricks with some additional plates on the end to act as fingers, and add some handles (via axles) at the bottom. If you use longer bricks at the ends then the middle pin would need to be offset from the centre to keep it smooth.

  • 3
    It's a time-tried classic
    – Joubarc
    Feb 1, 2013 at 20:33
  • 1
    Yes. I have tried that but I would like ideas more how to make the actual claw and how to make it open and close. Also the claw needs to be pretty sturdy and it needs to have good grip.
    – J. Walker
    Feb 2, 2013 at 16:55

I built a similar model to Zhaph's claw arm but with beams and a basic claw attachment:

enter image description here

360° Animation, Demonstration Video

I had a few problems operating the claw when I built it again with real bricks. If you collapse the beams too far, it can be difficult to open them again. When you try to pick up items with your tool, you also have to anticipate just how far the tool extends (try and possition the claw as close to the object as possible, the beams will push the object into the claws).

  • Well... I guess that would work... But I don't really like the part where to grab something it has to extend even more.
    – J. Walker
    Feb 3, 2013 at 19:12
  • @J.Walker I've built another model claw that doesn't extend, but it's not as reliable as the extending claw (and requires many, many more pieces). I'll see if I can make any more improvements before I share the design.
    – Ambo100
    Feb 5, 2013 at 20:07
  • I would prefer a different model from this to demonstrate a claw but this is good to. A three fingered claw would be a better model for a robot but this is the perfect model for a non-robot claw it's cool!
    – user3119
    Nov 21, 2013 at 20:42

If you don't need the arm to be extendable then you might get some ideas from the various Technic sets that feature cranes or claws, like the 8868, 8479, 8436, 8110 or 9397.

These offer multiple alternatives, as in pneumatical or purely gear-driven solutions, can be scaled up with appropriate supports and mounted on your own arm designs.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.