Introduction: CARDBOARD Robotic Hydraulic Arm

About: We are two young inventors, Kousheek Chakraborty and Satya Schiavina. We like using digital fabrication, electronics and various other fields of knowledge to create projects that focus on simplicity, efficienc…

Hello Instructables!

In this Instructables we will be showing you how to make your very own Hydraulic Arm! This project focuses on the principles of hydraulic movements. To do that we made a small scale demonstration of a Robotic Hydraulic Arm. We managed to do some pretty cool tasks with our ''Arm'', do check out the video down below for a better understanding!

This project is entirely made with cardboard and a couple of syringes, all the plans and blueprints are available. What are you waiting for? Let's get making!


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Step 2: The Materials Needed:

One of the reasons that this project is fun to make, is because the materials needed are very cheap and can be easily found at home!


  • CARDBOARD ( preferably a double corrugated board although you could manage with a single corrugation. Will result to a slightly weaker model.)
  • 10 ml SYRINGES x 8 (these syringes will act like the muscles of the hydraulic arm)
  • 2m long TUBE (the tube needs to fit snugly into the opening of the syringe.)
  • SUPERGLUE (you will need a lot!)


  • X- acto knife
  • A pair of scissors

Let's get making...

Step 3: Making the Blueprint

The whole design fits on to two A4 size sheets. We first sketched the parts and then keeping in mind the mechanisms made the blueprint.

I have made this step much easier for you guys, all you need to do is to print out the templates in the next step. If you wish you can tweak the design as per your looks : )


We designed all the parts so that you don't have to measure and draw. Simply print out the two files, with the same scale, all parts are in their right dimensions. Stick the printouts onto the cardboard and get making!

The toothpick holes are there too, if you have any other doubts we have uploaded lots of pictures so that you have a better visual understanding! Happy Making!


Follow the templates and carefully cut out both the Arm Support and Forearm. Note that I had started it out with a single corrugated cardboard but then I had to strengthen it by adding a second layer.

Start by making a rough cut and then repeatedly cut deeper and deeper until the piece pops right out, don't force!


Once you have cut out the gripper you can proceed to making the holes.


All the points on the templates are where the holes should be. These holes are the size of your toothpicks so find the appropriate bit. Start by poking the tip of your knife to form a small dent, a guide for the bit. Then carefully drill out all the holes and you are ready to start assembling the ARM.

TIP : You will notice that just by the weight of the drill the hole gets poked. though the small spacers tend to fold and get ruined. To avoid that from happening you can push through a screwdriver instead.

Step 8: Dry Fit

I would advise you to start by assembling a dry fit to make sure you know which piece goes where. This will avoid any mistakes or confusions later on. The plans are well explained and I don't think you will have any problems in following them : )

This pictures will give you a visual idea however

Step 9: Masking Tape to the Rescue

You will notice that the ends of the pieces with extensive use weakens and starts separating. We found an easy way to fix that by covering all the edges of the pieces with strips of masking tape! This not only strengthens the whole structure significantly but also adds a nice look to our model!

Step 10: Preparing the Syringes

Take four syringes, these will be the ones attached to the Arm. To attach it in a way that the joint can still pivot you need to adjust the syringes like so.

  1. Clip the extra plastic piece on top as it can cause unnecessary width
  2. Drill a hole around half a cm from the top of dia the size of the toothpick. One out of the four syringes will have two holes at the top, this being the gripper's syringe.
  3. Get two zip ties and close them in this ''figure of eight'' shape. Tighten one loop around the syringe then slip in a toothpick on the other one and tighten it till it bits tightly, finally clip the extra bit of the zip tie.

The pictures will remove any doubts!

Step 11: Rotating Platform

To make the rotating platform, find an old pen cap, you will use that as the axis on which the arm rotates on. Cut a piece of cardboard with length and width little bigger than the Support pieces.

Make a hole in the center with dia a bit bigger than the pen cap's, to permit easy movement. Stick the piece with superglue to the support pieces. Then grab a much bigger rectangular cardboard piece to form your base. Like before drill a hole in the center this time so that the cap fits snugly. Push the cap in and put dabs of glue for strength. Then slip in the main body...

Step 12: Rotating Platform Mechanism

Now that we have the mechanism ready it's time to add the syringe. Cut the pieces and stick them together like in the pictures. Then attach one end of the syringe to the newly made piece. Stick the piece with superglue onto the main body, all that's left is to compress the syringe and simply insert a toothpick into the base. this will automatically fix your syringe and convert the movement into a rotation of the arm.

Step 13: The Gripper!

Insert the semi stiff copper wires in the inner holes and bend them outwards so that they cant come out. Then twist each one into their respective holes in the syringe. I bent two small pieces of cardboard around a ruler to give me my end of the gripper. To add grip we cut out two tiny rectangles from an old ''Yoga Mat'' and stuck them at both ends. Fix the syringe and stick the triangular part of the gripper to the arm.

Step 14: Snip the Ends

You are almost done, just clip the ends of the protruding toothpicks.


Mix 4 colours with water each in a glass, and fill the 4 ''controllers'' (remaining syringes). Then cut your tubing into four equal parts. Attach the end to the controller and squeeze the syringe till water starts coming out at the other end. This is to make sure you don't loose any pressure. now attach the other syringe ( the one in the arm) making sure it's fully compressed.

Press and pull to see the magic!

Step 16: It's Complete!

And it's done! Now go ahead and test your new Hydraulic Arm. Go pick up a can and try to place on a given target. Show it off with your friends!

The simple Hydraulic System is what makes this project really stand out and the fact that it's so easy to build. Hope you enjoyed this instructables, see you next time!

Cardboard Contest 2017

First Prize in the
Cardboard Contest 2017

Robotics Contest 2017

Participated in the
Robotics Contest 2017