Build a Polar 3-D Printer From Legos




Have you ever dreamed of having one of those replicators from Star Trek? Ever wanted to make just about anything at the flip of a switch?

Well guess what? You're in luck, because in this Instructable I will show you how to make the closest thing to a replicator that current technology can manage; a 3D printer.

Wait a minute, isn't there another Instructable on how to make a 3D printer from Legos? Yep, there is, but this 3D printer is different; it's a polar 3D printer and it's capable of printing out so much more than just chocolate.

Now at this point in the intro you're probably thinking what do I mean by polar 3D-printer. Is it a 3D-printer that only works in the in the polar regions?

A polar printer is a printer whose principal axes, or how it can move, are radius(in and out), angle(spin clockwise/counter clockwise), and as opposed to a Cartesian printer whose principal axes are X(left/right), Y(up/down). In other words, it moves just like a polar coordinate system.

So why did I make a polar 3D printer instead of a good ol' Cartesian 3D printer?

1. I didn't have enough Legos to build a Cartesian printer.
2. I hope to eventually add a 3D laser scanner to it so I can scan in objects and send them to another printer somewhere else in world. Making sort of a 'teleporter'.

Before I begin this Instructable, I must remind you all of something; I have not yet finished developing control software for it.

Before you start posting variants of "This Instructable sucks" in the comments, I would like to remind you of something, the Altair 8800, the world's first successful personal computer, the computer that is the reason why you are able to read this Instructable and post derogatory comments, came with no control software either. But the Altair 8800 had prospects and it ignited a revolution. In fact, Bill Gates and some friends started Microsoft by writing software for the Altair.

I hope that this 3d printer will ignite the 3d printing revolution, so build one and join the revolution!!!

I would also like to thank the people at for their help and support.

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Step 1: Materials, Aka Time to Start Cannibalizing Your Lego Models for Parts

1. Legos(rare parts below)
-10 worm gears
-5 gear racks
-1 Mindstorms NXT smart brick
-3 NXT motors and cabling
-1 Mindstorms RCX smart brick or an NXT smartbrick if you have two

2. The Ultimate Fabric Painter, available at hobby/craft stores for about $20.

3. an aquarium air pump and tubing. Don't use the included air pump as it simply isn't powerful enough. Usually about $5-$10

4. a Lego table; I bought mine at a garage sale for about $10.

5. frosting, I used easy flow decorating icing. About $5

6. 1 transparency sheet or some wax paper. NOTE: if it is for inkjet and laser printers, wash the inkjet side off.

7. scotch tape and duct tape

8. Hot glue gun(tool)

7. Scissors(tool)

Step 2: Turn the Ultimate Fabric Painter Into the Ultimate 3D Printer Extruder

First of all, The Ultimate Fabric Painter uses an air pump to push fabric paint out when you cover a hole with your finger. Because we are using the Lego pneumatic switch to control the air flow we need to plug up this hole with hot glue.

Next, we apply a little bit of duct tape to the blue part, as it tends to pop out under pressure.

You also need to cut down one of the blue tips to a length of 3 centimeters. Make sure the cut is clean and flat.

Step 3: Make the Extruder Control Valve

I have provided pictures of my extruder control valve below, I intend to add LDraw models as soon as possible.

Then attach the Lego pneumatic tubing to some Lego tubing so that it fits some aquarium tubing and the extruder tubing. If the aquarium tubing doesn't fit wrap a rubber band around it.

Then attach the hose to the aquarium air pump to the middle air port on the valve and the hose to the extruder to the right air port on the valve.

If you have any questions about construction, please post them in the comments

Step 4: Build R-Z Module 1 Aka Move in and Out Thingie

R-Z module 1 moves the extrusion head along the R axis and allows for movement along the Z axis. Basically it just moves the extrusion head in and out. If you have any questions please ask me.

Step 5: Build the Z Actuation Module

The Z actuation module moves the extrusion head up and down with screw lifts. It is not yet completely automated. Currently, I control it manually with a Mindstorms remote.

Step 6: Make the R Axis Actuator Aka Spin Out With a Turntable

The R axis actuator rotates the extrusion surface like a turntable.

You also need to cut some transparency sheet to the shape of the extrusion table. If the transparency sheet is that inkjet printer/ laser printer stuff, rinse the inkjet printer side off. Then tape it to the extrusion table with the inkjet printer side down

Again, if you have any questions ask me.

Step 7: Putting It All Together

First attach R actuation module to the screw lifts with the pinch-grip as shown to keep the threading in.

Then press the extruder into the first hole in the first hole in the R- actuation bar.

Then tape the extruder hose to the motor as shown.

Attach the extruder control valve to the location shown in the picture.

Attach the smart bricks to the table wherever you find convenient

Then connect motor port A to the turn table, port B to the R actuator, port C to the extruder control valve.

I usually keep the aquarium air pump under the table on carpet to dampen the sound.

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    110 Discussions


    Question 5 months ago

    can this print plastic ?


    1 year ago

    I made it and I wanted to know if there was a cheeper way of making it because I spent about $75 and it was a lot compared to what I usually spend on projects like this.


    7 years ago on Introduction

    Where might you get a Mindstorms RCX smart brick cuz it doesnt come with the 2.0 set.


    Reply 7 years ago on Introduction

    When I first saw the instructable, I thought he would have used and Arduino. I think this is the perfect app for those remarkable little computers.


    7 years ago on Introduction

    Just so you know: this is not a 'polar' 3D printer. The words 'polar' and 'cartesian' refer to coordinates in TWO dimensions. The proper name for this printer's coordinate system would be 'cylindrical' as opposed to the other two common 3D coordinate systems, rectangular and spherical. Although I understand that saying that this is a cylindrical 3D printer would be confusing because the word also refers to a particular shape, same goes for 'spherical' and 'rectangular'.


    One of my pet hates is the pluralization of 'Lego'. It seems to be an entirely American thing. Here in Ireland we say 'I built a house out of Lego', as opposed to 'I built a house out of Legos'. Basically, we use the word like you would the word 'Wood' (Try saying that 10 times quickly!) Sorry for my little rant...

    3 replies

    Ahh the Lego/Legos debate haha. I've read an announcement directly from TLG (The Lego Group) that neither LEGO nor LEGOS is correct when referring to individual pieces or sets. LEGO is a combinations of the Danish words for "play well" (leg godt) and is the brand name. When referring to individual pieces or sets, it is correct to say LEGO bricks or LEGO set but not LEGO by itself. This seemed to make sense to me and was a good answer to the debate but then I saw another announcement that said the company didn't care much so I don't know if there's anything official. Calling them Legos is definitely something I've heard a lot and seems to be the most popular way to refer to them in the US. I guess in the end whether you call them LEGO or LEGOS people still know what you're talking about and it's still a great line of building toys.


    Reply 8 years ago on Introduction

    I think it's because we consider each brick or part to be one "Lego" (even if it's not Lego brand).


    Reply 8 years ago on Introduction

    yeah, because i have x-many lego bricks so i have x-many legos, and sometimes we can pluralize wood, but it is kind of slang, as in I am going in to the woods, as a synonym for forest (but forest sounds much more significant and magnificent)


    8 years ago on Introduction

    Can the fabric extruder handle the plastic in regular printers?


    9 years ago on Introduction

    Umm replicators are from Stargate SG1 not trek the closet thing i've seen is the borg

    1 reply

    Reply 8 years ago on Introduction

    Replicators are from Star Trek. They're the devices they use to create pretty much everything, except when it's convenient for a plot for the material to be un-replicatable.