Part 1: Fixing Up A Cheap 3D Printer – Buying A Cheap 3D Printer [From Craigslist]

In this series, I am going to show you how to fix up a cheap 3D printer so that it prints just as well as the best 3D printers on the market today. I start by telling you how I bought my printer off of Craigslist. I strongly suggest that you do not do this unless you have a lot of experience with 3D printing already.

The story begins on a cold night in February evening…

I had just seen that the new Prusia i3 Mk3 had been released, and it got me thinking:

How much effort would it take to fix up a cheap 3D printer so that it printed just as well as a top of the line Prusia?

How much would that cost?

Are those cheap printers from China actually usable?


I was browsing Craigslist while I pondered these questions, and by coincidence I stumbled across this listing:


Prusa I3 V2 3D Printer kit – assembled

3D Printer found on Craigslist

I’m selling this RepRapGuru Prusa I3 V2 3D Printer kit for $200.

It’s mostly assembled, needs to be calibrated.


Bingo. I have been on craigslist for a long time, and I’ve never seen a 3D printer for sale before. This was a rare find.

I wasn’t sure how good this printer would be. I wanted something cheap, but functional.

I decided to check for reviews online to see what others had to say about this kit. I found this RepRapGuru kit selling new on Amazon for a lot more than the price on the craigslist post. RepRapGuru also had good reviews and good ratings.

After more googling, I found that RepRapGuru offers a lot of instructions and tutorials for building the printer, which not every 3D printer brand does. If I got stuck or the other person had done something wrong, I could use these instructions to troubleshoot:



The person selling the printer had already done a lot of the work of putting the thing together. That made me a bit curious about why they were giving it away. Maybe something was broken?


So… to buy or not to buy?


To a seasoned veteran of the 3D printing world, this machine probably looks like a piece a of junk (or close to it). It violates several of the basic guidelines for buying 3D printers:


Basic Guidelines For Buying 3D Printers

  • Don’t buy a cheap Chinese manufactured 3D printer
  • Don’t buy a 3D printer with an acrylic frame
  • Don’t buy a used 3D printer


But to me, this thing was perfect.

I decided to fix buy it, fix it up, and answer one of the most tantalizing questions in 3D printing:


“Is it possible to buy a cheap 3D Printer and make it as good as a top of line printer like the Prusia i3 mk2 for less money overall?”


I texted the phone number on the Craigslist ad and received a response right away. His name was Paul.

He was an hour away in a rural place and wanted to meet up at a public place, which is completely understandable. After all, anyone who is willing to drive out into the country-side on a cold February evening to buy a 3D printer is definitely a weirdo.

We agreed to meet at a Walmart near his house. So I pulled on my boots and 5 minutes later I was on the road heading out into the night.

An hour later I pulled into the Walmart parking lot and found an empty spot toward the back of the lot. Then I pulled out my phone.

“Here,” I texted.

“OK, be there in a minute,” came the response.

What happened next has got to be one of the strangest, most hilarious experiences I’ve had in a long time.

If you’ve ever met up with someone to buy or sell something from craigslist, you may know that it sometimes feels like you are showing up to the meeting point ready to fight.

It’s hard to explain, but buying things off of craigslist feels kinda dangerous:



Paul pulled into the parking lot in a big black truck. He parked and got out… and then some other guy got out of the passenger side also.

They were both wearing camo gear and easily a foot taller than me. I waved to them and Paul waved back, but the friend didn’t respond. He just lit a cigarette and leaned against the truck, staring at me.

I walked over a greetings were exchanged. Paul seemed like a friendly guy and started telling me that he had tried to sell the 3D printer a few times, but I was the only person who ever showed any interest in it.

He opened the back door of his truck there was the printer. It looked exactly like the picture. It was in a cardboard box and mostly assembled.


Walmart Parking lot at night


I glanced over it and couldn’t see anything obviously wrong with it. All of the motors were there, and the controller and power supply were both mounted. The only things missing was the spool holder, but the parts were there, so I could put it together myself.

When I asked why he was selling it he said, “there’s a lot to learn, and this one has to be calibrated still.”

I had read about how difficult it can be to calibrate this model and other’s like it. I didn’t mind. In fact, that was something I would try to improve.

“Also,” he added, “I’m a CNC guy. Additive manufacturing isn’t my thing.”

I heard a footstep behind me and turned around. Paul’s silent friend and come up behind me, still leaning on the truck and smoking. He was still just staring at me.

“Great, well here’s the cash,” I said, handing him a wad of $20 dollar bills.

He counted it. It was all there, of course, so Paul stepped aside. I grabbed the box with the printer and thanked him as I walked quickly away.

“Nice to meet you,” I said to the creepy friend. His expression never changed.


The Drive Home: What A Time To Be Alive!


On the drive home, I sailed through the winding country roads with one thing on my mind:

I just bought a second-hand robot from a random person in a parking lot…

I felt like a customer meeting Watto at his junkyard on Tatooine.

The fact that I am alive at a time when shady robot deals on a semi-black market are a thing is hilarious and amazing. It’s moments like these that really drive home the fact that we are living in  THE FUTURE

The 3D printer sat next to me on the passenger seat, and every pot hole I hit caused the delicate mechanical parts and wiring to bounce and shake.

Leonardo_da_vinci,_Flying_machineImagine if Leonardo Da Vinci had seen this machine. He would be astounded by it’s beauty and simplicity.

Imagine if Michaelangelo had found one of these strange contraptions in his studio one morning.

What do you think these master creators would have done with it? Would they have tossed it aside in favor of the simpler movements of the hand and eye?

Or would they have used this fantastical tool, which feels so much like a renaissance creation at its core?

After all, leaving aside the raspberry pi, the electrical power, and the plastic materials, the design of this machine is no more complicated than Leonardo Da Vinci’s flying machine.

As I neared my home, it struck me for the first time that the design of a 3D printer is a sign of our cultural debt to the renaissance.

The fact that a man named Dr. Adriane Bowyer could create a machine in his lab with such audacious and simple designs, and yet also have such vision as to create it with the intention for it to be self-replicating – that is pure renaissance.

From there, the history of the Enlightenment echoes through the ethos of the 3D printing community whose members are staunch defenders of open source, freedom of expression, and rights of the individual.

Our mechanical, industrial, victorian heritage speak through the 3D printer’s motor, as well as it’s mass produced metal parts.

As a final touch, this post-modern neoliberal age of global trade finds its foundation in the parts sourced from China (though Rep Rap Guru is itself manufactured in the USA) and the fact that the entire contraption is controlled by a computer smaller than my hand yet more powerful than any computational device ever created before 1980.

All of that, and I just bought this thing in a random parking lot somewhere out in countryside…

What a time to be alive!


What To Do After You Buy A Cheap 3D Printer


After my long drive home, musing about the history of ideas, I parked my car and gently carried my newest contraption inside.

I was super excited and the boredom I had felt hours before was long gone.

Step 1: Make Sure You Have All Of The Parts And That Nothing is Broken

The first thing I did was assess the condition of the printer. I took the 3D printer out of the box and put it on the floor along with all of the extra parts that it came with:


Cheap 3D Printer from Rep Rap Guru


My initial impression was that it looked good. I noticed that the acrylic frame was very unstable as I put it on the floor.

But there were no obvious cracks in the frame build plate, which was a small miracle.

I also took a closer look at the other parts and extras that came with the printer. Everything seemed to included and nothing was missing, except for maybe a glass plate that would be attached to the build area. That is easily replaced though.

Everything essential was included. There was even a nice note from Rep Rap Guru giving some helpful advice and steering to their google doc full of build instructions.

The guy who sold me this printer did a very good job packaging everything up. The attention to detail and the care it took to make sure everything that came with the original kit was included meant a lot to me.

>>>> THANKS PAUL <<<<

3D Printer PartsSeriously, Paul, wherever you are and whoever you are, thanks for taking the time to include everything in the box. It saved me so much time and energy.

Otherwise, I would have had to figure out what was missing, which is super tedious, and then buy replacements.

Step 1a: If something is missing or broken, make sure to contact the seller and find replacements.

I didn’t have that option.

After all, if something had been missing, it’s not like I could have returned the printer to RepRapGuru. I didn’t have the reciept or any proof of purchase. The warranty had been voided long ago and there was no way they would send me replacements.

[Although, I have read many reviews saying that RepRapGuru customer service is top notch, so maybe they would have done me a favor there… hm..]

I can also finish putting this thing together with it’s original parts so that we can take an honest look at how much effort it will require to improve this 3D printer out of the box.

Again, Paul, thank you!


Step 2: Clean Up The Printer And Parts If Needed And Prepare Your Work Space

As you can see, the wires were a mess:


Tangled wires 3D Printer


So I popped open a beer and began the pains-taking work of untangling the wires.

Some of the wires were so tangled that I don’t know how they were even put together. Several of the Arduino leads were woven through each other in a haphazard way.

I had to unplug a lot of the wires just to see what was going on:

Untangling 3D printer wires

Untangling 3D printer wires


This process took a long time, but I enjoyed it. I still had some of the adrenaline that comes from starting a new project to help me push through.

During this process, I also noticed several spots where the printer had not been put together in exactly the right way.

For instance, one of the connections on the power supply was loose and would have to be tightened. There was also a screw missing from the Arduino mount, and several other screws were not very tight.

Arduino mounted on a 3D printer

I know that with acrylic frames you have to be careful not to tighten them too much or else you will crack the acrylic. Rep Rap Guru is constantly reminding you of this fact in their documentation.

As a result, it’s best to tighten screws by hand and never force any plastic part into place.

In fact, this is also what makes acrylic frames so wobbly compared to metal frames: everything is just not quite tight enough.

But the screws that I found that needed tightening were just plain loose. And as I mentioned, one of the screws that hold the Arduino onto the frame was missing.

I actually ended up removing the Arduino completely so that I could make sure it was attached properly. It also looked a bit dusty, so I decided to dust it off a little bit.

When I removed the Arduino, I discovered something else slightly amusing about how it had been mounted:

A screw had been inserted into the Arduino before the top board had been attached, and instead of redoing it, they had just continued on mounting the Arduino.
Arduino side view

Now to be fair to Paul, this doesn’t really matter in the grand scheme of things. Inserting the crew through all of the holes in the Arduino isn’t going to affect the print quality or performance over time at all.

But I am a bit of a perfectionist so small things like this matter to me. So I decided to take off the top board and insert the screw through all of the holes.

Untangling all of the wires also gave me the opportunity to inspect most of the key parts of the printer up close.

I checked the hot end to make sure it moved smoothly along its axis.

The belts were not fully trimmed, but this probably isn’t going to be a big deal. Still, I will probably remove the excess belt just to be sure that the ends of the belt don’t interfere with the movement of the hot end.

3D Printer hot end extruder

On first inspection all of the motors and key elements looked like they were in good shape.

I dusted off all of the fans and checked for any signs of wear and tear on the pulleys. But I couldn’t find a single indication of damage anywhere on the machine.

There wasn’t even a scratch on the build plate. I would of course have to replace missing plate of glass, but otherwise the machine was in top shape.

I used twisty ties to hold all of the wires together and separate everything out.

It took another half an hour to finish unplugging everything and untangling all of the wires.

In the end I was left with this nicely organized, dust free 3D printer:

Almost complete 3D Printer


The only thing left to do was put the printer onto the table that would be my workspace for this project. I also had to make sure my tools were ready, such as my digital caliper and smaller screw drivers.

Once that was done, I was ready to start the next part of this 3D printer rehab job.

Everything was prepared and read to go. I will say that I got lucky with this printer. It was surprisingly easy to unpack and prepare for the next stage.

I am very grateful to RepRapGuru and Paul for keeping this printer in such good condition.

I know that not everyone is as lucky.

A Mysterious Love Note: 3D Printers And Romance

I will leave you with this tantalizing note I found on the box after I set up the printer:

3D printer love


In beautify cursive hand writing, it says:

To Paul

Love Laura

If you can read this the invisible wrapping paper worked!

We will be rich!


Who is Laura? Paul’s girlfriend? Did they break up and this is why Paul sold the printer?

Or is Laura his mom?

So many questions that will never be answered.

But one thing is certain: 3D printers are romantic!


In part 2, I will finish building it and calibrate it, and hopefully even print a first benchy!


Leave a comment below if you have a question about buying a cheap 3D printer, or if you have any questions about how to fix a cheap 3D printer and improve it.

While I don’t recommend that you purchase a cheap 3D printer in the first place, I am happy to talk about cheap 3D printers with you.

The whole point of this experiment is to figure out if there is enough value in a cheap 3D printer to make it worth purchasing and fixing up. I’m really interested

It’s important to figure out whether you can actually work with it before deciding to .

I’m always happy to help 🙂

Stay tuned for Part 2.

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