Hiro's Fight Robot From Big Hero 6




About: I'm a social-worker, working with 12 - 23 year-olds. I used to be a printer. In 2018 I opened a small makerspace (www.imdib.nl) in my house, where I have lasercutters, 3d-printers, Arduino's, Mindstorms and ...

After seeing Big Hero 6 for the first time, it felt like Hiro's robot was ideal to make with the 3D-printer.

I think that Hiro also might have used his 3D printer to build him. Hiro used some kind of magnetic system for his robot. I want to make just a model and thought that bungee cord must be the way to go.

First I tried to print just the 9 parts, but I didn't like the result so I decided to print al the parts in two pieces.

The head and the bottom ball are the same, but for the middle ball I used a different design. All in all there are just three different parts to print.


Step 1: You Will Need


  • Bungee cord (5 mm)
  • Acrylic paint (yellow and white)
  • 3D filament


  • 3D-printer
  • Sandpaper
  • Super glue
  • Sharpy
  • some metal wire
  • Brushes
  • One M5 bolt
  • Scissors

Step 2: Print the Parts

I designed the parts in 123D-design, so I added both the STL files for printing and the 123dx files to tinker with.

It was kind of hard to come to the final design, because the dimensions aren't the same in every shot of the movie.

All the arms, legs and ears are the same, so you can print that file six times.

The head and bottom part of the body are also the same, so you can print "body2" two times.

Body3 is the middle part of the body. You have to print half of the ball two times.

All 9 parts of the robot have two pieces, so in total you will end up with 18 separate pieces.

I used a Robo3D with PLA. No raft, no support.

Step 3: Prep the Balls

To make sure that both halves of the body-balls fit nicely, I sanded them on a flat service.

Next I glued the halves for the head and the bottom ball together with super-glue. (Don't glue the middle ball yet)

On the one that is going to be the head I drew a circle where the face will go. I used a metal ring for this, but something like a toilet roll would also work.

Step 4: Prep the Arms

I also sanded the two parts of the arms that will go together.

I pushed in a M5 bolt to align the two parts and glued them together with super-glue. If you use to much super-glue it might be hard to get the bolt back out.

Do this for all nine arms (legs and ears).

Step 5: Add the Bungee

  • Put a knot in one side of the bungee cord. You will need a piece that is long enough to go trough the three balls.
  • Cut the bungee just above the knot.
  • Push the bungee through the middle of the 'head' ball, entering on the side with the wider hole.
  • Pull the bungee through until the knot is al the way inside the ball.

  • Put a knot in an other piece of bungee. This must be long enough to go through two arms and one ball.
  • Push this bungee through an arm, entering from the smaller side of the arm.
    -pushing it through was very hard, so I made a hook out of a piece of metal wire to pull it through-
  • Now pull it through the slits on the side of the ball that already had a bungee going through the middle. The new bungee goes over the knot in the old bungee, so they should not meet each other in the ball.
  • Pull this bungee also through the other arm.
  • Pull the bungee out a little further (it is elastic) and put a knot in it.
  • Cut off the excess bungee at both knots.

Step 6: Add the Next Pair

For the middle pair, you first bind the two arms together the same way, only this time without the ball;

  • Put a knot in one end of a piece of bungee.
  • Pull the bungee through both arms, with the thick parts in the middle.
  • Put a knot in the other end of the bungee.
  • Cut off the access bungee from both sides.

  • Put the bungee that is coming out of the head and push it through one half of the middle ball.
  • Pull the two arms apart and push the bungee that is in between the two arms, in the slit in the half ball.
  • Put the other half of the ball on the bungee.
  • Glue the two halves together.

For the bottom pair, you put the ball on the bungee and than put the legs on;

  • Pull the bungee that comes out of the other two balls, through the middle of the last ball, with the wide hole on the bottom.
  • Pull the bungee hard through and put a knot in it.
  • Cut off the extra bungee.
  • Pull the knot all the way into the ball.

  • Put a knot in the final piece of bungee.
  • Pull it through the legs, ball and other leg, like you did with the first one.
  • Put a knot and cut it clean.

Step 7: Paint the Face

I used acrylic paint to paint on the face.

The robot in the movie had his face painted on a little bit sloppy, so that is where I am going for.

I needed five! layers to get a nice coverage of yellow.

The white only needed two layers.

The black I did with a sharpy.

I am very happy with the result!

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    41 Discussions


    Question 8 months ago on Introduction

    My son is dressing up as Hiro for Halloween this year. We are trying to get / make the megabot for him, with no luck. Are you selling already made megabots or the parts to put together? We do not have a 3D printer.

    Thank you

    3 answers

    Reply 8 months ago

    Hi, That is really cool. No, I don't sell or produce them. If you live close you would be able to come and print it at my makerspace, but I don't think you do (because we don't do Halloween in the Netherlands) Perhaps there is a makerspace near you where you can print it? It is an easy print. I think that painting on the face is the most challenging part of the whole process. It does take a long time to print all the parts, but that is with all 3d printing. Good luck with getting the costume ready!.


    Reply 8 months ago

    That is really cool. You will need arm31 and arm32 both 6x. The file body 2 has two parts in it and you will need both 2x. The file body3 has only one part and you need that part also 2x.


    2 years ago



    2 years ago

    Nice one. My kids and I love that movie much. Six young makers with cool inventions ^_^

    6 replies

    Reply 2 years ago

    Exactly. •-•
    This might be a cool thing to make for (or with) your kids than. The result is really kid-proof and almost impossible to break.


    Reply 2 years ago

    Unfortunately I don't have a 3D printer, and no one is hiring it in town either. So maybe one day I will made one carving wood pieces :D


    Reply 2 years ago

    You can always order from 3D print providers like shapeways or maybe something more local :) Maybe someone's willing to print and send to you.


    Reply 2 years ago

    Or make my own 3D printer maybe :D

    There are dozens of DIY 3D printers on Instructables, but I am just not interesting in building one yet :D Maybe one day...


    Reply 2 years ago

    That would actually also be a really cool project. Perhaps you might win a 3d-printer with it when you add it in a challenge on Instructables ;)


    2 years ago

    Cool, may be even cooler cobmine string with neodymium magnets.


    2 years ago

    My son is taking all my screw driver bits and treat it as a microbot, so I'm planning to build this one using wood.
    Thank you so much for saving my tools lol!

    3 replies

    Reply 2 years ago

    I never noticed, but those bits do look a lot like a part from a microbot. Good luck with that ;)


    Reply 2 years ago

    Actually Hiro based his Microbots with his fighting bot..
    My son is just 2 years old and he imagines things more than I do lol.

    I'm planning to do this on wood since he likes to chew things when he enters beast mode. I'm planning a Guava branch, we have a lot of that in the Philippines :)


    Reply 2 years ago

    I'm very curious how yours turns out, so please show your result.