Introduction: LEGObot 3D Printer

Picture of LEGObot 3D Printer
   Ever since I saw the first makerbot, I have been obsessed with 3D printing, I am an engineering student and I don't have an extra $800-$2500, and have been doing my best to create one out of what I have on hand. I tried using arduino with easy drivers, and parallel port, but neither one gave results, I always needed a tool or part that I couldn't get.  So I pulled out my old box of legos and started building.

   This is a project I have been working on for the past year, it prints in hot glue and is made almost completely out of legos. Its design is roughly based on the first version of the makerbot. While it does print, I would call this more of a prototype or concept than a finished project.  I am using 4 power supplies (3v extruder motor, 7.2v for nxt, 12v fan, and 115v for hot glue gun) and having to manually turn the extruder on and off, (although I am working on that one) . Unfortunately,  due to my lack of programming skills, every move has to be manually programmed from the NXT programming software, I have yet to find a g-code interpreter for the NXT.
  Hopefully in the next version I will be able to shorten the height of the platform, reduce wobble, and use g-code files.
But in the meantime, I have included a Lego Digital Designer file of the full printer, just about all the technic parts are exactly the same as in my printer, but for the structure I used different part placements to speed the digital building process, the structure and dimensions are still the same. under each X and Y axis there are 2 suspended blocks that I placed coins in to balance the weight of the motor on each side, for the extruder motor I used a lens adjustment motor out of an old VHS camera because it was low speed/high torque. In the .ldd file, the green box on the right side of the extruder gears is the case I made for it, it works perfectly.

   While hot-glue works, its very rubbery and doesn't have many practical uses, if only one or 2 layers are printed then it will stick to glass to make window stickers, but its not sturdy or rigid, I will be experimenting with printing using wax and heat-melting resins in the future. I am currently limited to what I can make with what I have on hand, some more printed parts could really improve accuracy on this.  I initially did not have enough gear racks so I asked someone who had a 3D printer at work if he could help me out, I was able to get around 30 of them printed, and while they work, they do not connect perfectly to the legos, which is what causes most of the wobble in the platform.

If you liked this and want to see more, please vote for it in the 3d printing and lego contests!


UPDATE: My project is now on Technewsdaily and Gizmag! Thank you Randal Marsh and Elizabeth Palermo for writing those excellent articles! also on Hackaday, Dvice, and many more!

Step 1: Instructions

Picture of Instructions

The ldd file will generate instructions for you, if you don't know how to do it, follow this.

1, Open the 3D printer.ldd file in Lego Digital Designer
2. Select "Tool Box"  from the menu bar
3. Click "Generate building guide"  or press "CTRL" and the "M" key together (in windows).
4. Wait for it to generate the building guide
5. Follow the instructions :)

This is not the same gear rack I had printer for my printer, but it looks like it would work better.

For those who can't open the .rar file or don't have WinRAR you can download the LDD file > HERE < from MediaFire
And for those who can't use Lego Digital designer, download the HTML instructions > HERE < from MediaFire

Step 2: Whats Next?

Picture of Whats Next?

Now that you have a 3D hot-glue printer, what can you with it?

Color your gluesticks

Print your own candy with sugar sticks! (might be a mess)

I'm going to be experimenting with pine resin based glue sticks, it melts in heat and cools hard, so it could be used.

If there are any problems, clarifications, or questions you have, feel free to post them in the comments and I will answer them as soon as I can!

I also am looking for a good name for this, if you have any ideas, or if you like LEGObot please let me know!



misdemeanour (author)2017-09-16

omg, omg, omg, omg

jonno51 (author)2016-04-01

This is brilliant, poetic, and generally pretty awesome. Try to find time and finish it because you are a genius.

ccncomm (author)2016-03-30

Why side lined? Legal or wife...or both?

ccncomm (author)2016-03-30

Why side lined? Legal or wife...or both?

SheldonH7 (author)2016-03-06

Shut me down. Lego making Lego, how perverse

MattyJam (author)2016-02-16


andrew_bentley (author)2016-01-26

Interesting project, too bad it's sidelined at the moment.

Darb27 (author)2015-11-01

Has the programming came out

matstermind (author)Darb272015-11-02

Not yet, it has proven more difficult than I first thought. this project has been sidelined for an undertermined amount of time.

Darb27 (author)2015-11-01

Has the programming came out

Darb27 (author)2015-11-01

Has the Programming came out yet

AnnaR9 (author)2015-08-13


We're looking to hire someone who owns a LEGO 3D printer for an event. We would pay for services, travel and accommodation. This would be between October 15-18.

If you would be interested, please get in touch at

Thank you!


matstermind (author)AnnaR92015-08-13

Thank you for the offer, however I would need to know more information before I can make a decision. What event is it? Where is it? and what makes my project so valuable to have expenses paid for this event?



citylife (author)2015-07-03

Could you tell me the detailed list of the tools needed to make this printer?

matstermind (author)citylife2015-07-03

the only tools used was the mini hot glue gun, a philips screwdriver to take apart the camera lens, and scisors to cut the sewing string. The rest is all legos. I did use a soldering iron to make a touch sensor as i did not have enough lego ones, but it functions exactly the same as a lego one.

MSM94 (author)2015-03-16

That is very interesting music. Where from?

98TheCiaran98 (author)MSM942015-04-11

its "Animusic"

smartmiltoys (author)2015-02-25

I like this project but it's like saying It cost me $0 dollars to build
my car because I made it from the parts I had lying around. I might
happen to have an engine, transmission, suspension, tires, and a frame
lying around but most people won't be able to build a car for less than
they could buy a car already made. Same thing here. Unless you already
have $700-900 of the correct Lego parts lying around most people are
better off buying a 3D printer kit.

divadg123 (author)2015-01-30

Dude this is so freaken badass!

It's awesome how you made this with legos and hot gluexD Very innovative!

TheTutor11 (author)2015-01-22

Hi, I love this project, I would love to build it for a local school. How much does it cost?

jdzach (author)2014-12-16

In your next version you should try mounting a 3d-pen they are around $80 i got mine for $60 so there a fraction of the cost of a 3d printer.

davidbarcomb (author)2014-11-30

Excellent project. I love it

jdzach (author)2014-11-27

I'm making my own version but I'm having trouble making the glue gun trigger squeezed. Any ideas?

matstermind (author)jdzach2014-11-27

I couldn't figure out an easy way to get a consistent rate of extrusion by squeezing the trigger, so i disassembled to hot glue gun, kept the heater and metal nozzle part, and used to gear assembly on top of the printer to push the glue through from the back.

williamntanujaya (author)2014-11-02

Do you know when the program will come out by?

I ave no idea how long it will take, i am just starting to learn labview, and a gcode interpreter is a fairly advanced program. So, if I can figure it out, it will take a long time.

You can remove the Lego Mindstorms electronics and replace it with a RAMPS board (It runs Repetier, you can find out more on the RepRap page). You can also replace the servos with basic $7 stepper motors to run with RAMPS. It costs around ~$30-$40 to implement this system. You can also attach a nozzle ($0.50) onto a high temp hot glue gun, and run PLA through it, since PLA's prime temperature is 190C (which is the standard temperature for high temp hot glue guns). ABS melts and can be used at 190C (I've melted lego's before at 70C) but the ABS does not stick to itself well. If you use ABS, it is also recommended to use a heatbed to prevent curling. Hope you have fun with this printer!

jgarza2108 (author)2014-11-11

can you make it less complicated to get instructions on the download

williamntanujaya (author)2014-11-02

Do you know when the program will come out by?

matstermind (author)2014-10-26

Its been put aside for a while until I figure out the gcode interpreter, I am currently learning labview and it looks promising. but it will be a while before v2 is posted.

jdzach (author)matstermind2014-10-26


Crafterkid123 (author)2014-09-15

could it make complicated cases with holes in the side without having the glue fall into where the holes are? or will i have to use an x-acto or a frame?? this is seriously the best 3d printer idea i've ever seen and it even looks like can make it myself :D. what files does it need to program the printer??

andytangtsk (author)2014-08-23

What if it runs out of glue while printing? As far as I know, these glue sticks runs out very quickly( Well, for my glue gun)

matstermind (author)andytangtsk2014-08-23

Ideally, each layer is as thin as possible, so the extrusion rate is set very low, but the size of the object is still limited by the amount of hot glue stored in the extruder. However, The extruder is designed so that it can be expanded to hold more hot glue.

andytangtsk (author)matstermind2014-09-15

Oh, thanks, great project and i'ble by the way

한민류 (author)2014-08-31

how can I make lego 3d printer? please tell me my mail. If you want.

XYZAidan (author)2014-08-31

Where does the string attach? I can see it is wrapped around the axles connected to the servo, but where else?

matstermind (author)XYZAidan2014-08-31

The string goes over pulleys in the top corners and then are tied to ball joint pegs below the pulleys.

henryqiu (author)2014-07-24

Damn, nice job, man!

matstermind (author)henryqiu2014-07-24

Thanks, i am still slowly working on version 2.

yomanurock (author)2014-03-24

how do I put together all the 'non-lego' pieces? I have the lego structure and now i need to put together all the non'lego pieces.

matstermind (author)yomanurock2014-03-24

reply is above. If you can, it would be nice to see pictures of your progress.

matstermind (author)2014-03-24

There are only two non Lego pieces, the motor for the extruder (which actually could be an old rcx motor or power fuctions motor, and the hot glue gun for the extruder. the hot glue gun needs to be taken apart and have the metal heater placed in the lego "jail" to hold it together. I took the printer apart a few months ago so i can't take any new pictures. but these three best depict the placement.

MasterChick (author)2014-03-07

Oh my… You made that?

spaktashabit (author)2014-02-17

could you use something like weed wacker line instead of hot glue sticks

someone_678 (author)2014-01-26

How does the hot glue come out and how do u make the extruder

matstermind (author)someone_6782014-01-27

The extruder is simply a hot glue gun with the plastic case and trigger assembly removed. A motor turns gears which pushes down on the back end of a gluestick and forces the glue out the front.

aneeshdua (author)2014-01-20

well pls tell me the approximate cost of this project....Thanx

matstermind (author)aneeshdua2014-01-27

I already had all the parts I needed, so I spent a total of $0 on it. I have no idea how much it would cost to purchase the parts new.

ManutoBck (author)2014-01-11

Sorry for be wearisome, but i relley need your help, anybody know how to put all the non-lego pieces??... I have all the Lego strucutre, but now, i don't know how to put the extruder and the non-lego pieces! Really thanks to sombody that can helps me... =)

About This Instructable




Bio: I am an engineering graduate who is constantly tinkering, making, and building. I have always enjoyed disassembling old electronics and re-purposing them. I enjoy anything ... More »
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