Maker News
Maker Spotlight: Meet Amelia Buns and Her Open Source 3D Printer Tool Changer

Based in Iran, Amelia is hard at work on a low-cost printhead tool changer for 3D printers, which allows for multi-material 3D prints among other potential functions. A maker of various smart and mechanical builds, her endeavors are impressive, and her creativity and enthusiasm seems boundless. We reached out to find out more about her.

Name: Amelia Buns

Social Media:

Where are you located?

I currently live in Iran.

What is your day job?

I don’t have a job right now. I’m currently working towards getting accepted in a university, I am also working on my projects on the side.

What kinds of stuff do you make?

I’ve made all sorts of stuff, from coding and simple game engines to IoT nightstands and circuits. I’ve always been very obsessed with learning, therefore most of my projects are learning projects. I make and try and mess with things to understand how they work.

When I saw the E3D tool changer I was like “I NEED THIS!” Well, as it turns out it’s ~$3000 and there’s no way I could ever afford that much, I thought to myself as a joke “maybe I should make a janky version of it myself for fun.” Back then, I didn’t believe in myself one bit, but a week later, despite others telling me I couldn’t make it work, I made the first prototype of my magnetic tool changer, the Doot Changer! The name is supposed to be a humorous reference to the E3D tool changer. 

It worked very well for a month until the printed coupling gave me issues. That’s when I came up with the idea of combining the coupling and magnets together. Reduced cost and metal on metal contact/wear were the main advantages. Everybody else I saw thought of these two as separate things but by combining them I had my Doot changer V1.5 (the magnetic ones are called V1.x) working very great! It costs $30 (most of that cost is because the magnets are bundled in packs of 10 — you only need 3) and can be added to any printer very easily, the files take 3 hours to print, they are fully free and open source and barely take any assembly or design. You just need 4 screw holes in your main carriage.

This is one of the first good looking prints off my printer! Keep in mind that Tool 2 (black) doesn’t have a cooling fan.

I really regret not testing a subtractive tool with this version. I have a feeling it’d handle that very well, despite using magnets. The main limiting factor after all are your steppers, not the magnets! (strong magnets need more force to separate).

After a while I saw the Joshua Vasquez’s Jubilee changer. I got interested in designing one that uses a motor, I call this one V2.x. It’s a lot more complicated and takes some effort to port to other printers. So I’ve built it on top of my own printer and motion system based on a HEVO frame. It’s fast and very accurate. I personally love it. I’ve been getting amazing prints off of it in single extrusion mode so far! Unfortunately living in Iran limits me in a lot of ways, so the printer is far less nice as I wish it would be. I would personally choose V-SLOTS for the X over a rail since it’s lighter and better if I could find one in my country! Although recently I saw one available in a random store… maybe i’ll experiment with it.


The whole printer (V2.0) costs anywhere from $650–750 so far. The tool changer + motion system is a cheap upgrade from a stock HEVO. The biggest cost factor is the linear rail, but it’s very worth it considering the quality and speed improvements. I’m very happy since there’s no proper tool changer out there that I know of in this budget range.

Some of the main savings come from the 3D printed dowel pin locking bar and wedge, a cheaper motor and being directly driven with a very lightweight motor, Getting enough torque out of that motor was a pain! I had to optimize every corner to get it working nicely.

How does the software on the Doot Changer work?

I use klipper! I did write some g-code macros and software to make it smart. For example, if it powers down mid-print, it remembers the tool it had picked and parks it. It’s pretty amazing for prevention failures, only possible with klipper. 

The picking is just going to the tool, locking it, and going back. Although there’s some special g-code to make it work better, etc. I might end up writing and making my own drivers for the tool lock motors with encoders. But I’m not sure if I will yet. I currently set up a durability tester that shows me how long a DC motor will last. It has simulated 4.5 months so far. I’m waiting till it reaches at least 9 months before I consider it acceptable. Otherwise I’ll go with my steppers.

How did you get started making stuff?

Honestly, I was always curious. My dad told me I used to take apart the devices in the house before I could talk. He caught me taking apart the radio once, I was trying to figure out how it works. My childhood drawing notebook was full of “inventions,” pretty childish ones that wouldn’t work obviously, but my point is I had a strange unending passion for design and science from as long as I can remember. When I was a kid I used to always buy and make pre-made circuit kits, but I could never figure out how they worked by looking at them. Thankfully as I grew older I learned English and figured out how to use Google to learn and teach myself. I made a lot of random robots and stuff. A DIY IoT nightstand, a robot that ran away when you tried to catch it (ultrasonic sensors :P) and all sorts of weird stuff.

My IoT nightlight

This is the lamp circuit. Really it’s just an ESP32 with a step down and some mosfets :). Back then I ran the LEDS as below the rated voltage and at a lower current so that I wouldn’t need to current control them. The brightness barely lowered anyways. I later designed my own circuit with LED controllers that use PWM to dim the lights, but after I finished it the sanctions got worse and I couldn’t order my circuit anymore, so I made it work another way.

I’ve also done a lot of embedded programming projects! 

Do you belong to a makerspace/fablab/hackerspace?

Nope. I doubt we have those in Iran, But I’d love to join one. It seems like a great way to meet similar people and gain access to resources that are too expensive otherwise.

What is something that you’ve made that you’re really proud of?

Well the Doot Changer. People told me it wouldn’t work and I didn’t believe in myself either. I was in shock at 5am when I managed to get it working so well! It was a big deal to me, especially considering how limited my resources were in such a country, instead of being sad about not having access to a lot of parts, I found ways to work around them!

There’s also my game engine that took a lot of effort to write in OpenGL. Keep in mind it was a simple engine with basic lighting and model loading capability. No animations etc. It was just event handlers and model loaders and lots of shaders and openGL code with shaders and all that.

There’s also my ILI9486 library for the STM32F4. It took so much effort, especially due to a wrong datasheet from ST Electronics… My memory is very weak so I can’t think of much else right now! But I’m personally proud of these. It took a lot of effort and I managed it despite my mental health and physical health so I’m proud :). The IoT nightstand also turned out very pretty in the end. I regret taking it apart.

I tend to focus more on learning rather than making, but I feel like as I learn more I have more ideas to make.

What is next on your project list?

The Doot changer is taking all of my day right now, But I’d love to design a tilting hotend setup that uses a single stepper for dual-hotend direct drive extrusion. The mechanism is simple but making it work and compact will be another challenge..

I also wanted to try my luck at making my own carbon fiber laying tool.

I also really wanted to make my blinds controllable from the internet too. It sounds fun and useful.

I also want to experiment with a hall effect sensor as a 3D Printer’s bed leveling sensor. Instead of probing I want to run it over the bed and measure the distance every millisecond to create a high res map!

I also wanted to make a selector-style extruder that uses 2 motors for, say, 5 hotends! It’d be fun!

I also really wanted to experiment with DIY laserjet printing/colouring or SLS but I doubt I’d get far!

I also want to try using a small cheap BLDC for my extruder. It’d weigh only 30g! Maybe even a simple geared DC Motor. Same with the XYZ axis! I wonder how that’d turn out!

Oh and probably the coolest one would be a cheap muscle-restricting VR glove. It’d be a simple spring-loaded disc with a string around it. Just by itself it would always keep the string at a tension, but with a motor/solenoid/magnet or whatever, I could add a brake that only lets you move your fingers backwards. as if you’re holding into something. adding a simple encoder wouldn’t be that hard either. In theory it’s very cheap. reality is often disappointing tho. I would love to do the same for the entire arm.

I also want to really work on this game idea I have. It’s a VR game. It’s a game about taking care of little blob creatures! It’s all scripts and mechanics written now. But I hope one day I’ll make it! I’d describe it as a mix of Slime Rancher/Stardew Valley and a bit of my own stuff.

I also wanna really experiment with a different kind of tracking for VR, using radio signals. But I doubt I could get it working cheaply with +-1mm accuracy. If I ever do however it’d have many advantages.

What is something you’d like to work with but you haven’t yet?

So many things, living in Iran means limited access to most things and some things are too expensive for me.

CNC machines are one of them! I also always wanted some of those fancy stm32f7 boards with a capacitive touch LCD, but they seem very complicated and expensive.

I also really wanna mess with encoders and brushless motors. Luckily that is something I can get in Iran. Just not the specific type I wanted.

The list is very long tbh, but these are what’s on top of my head. I tend to try to forget about what I can’t do to avoid getting upset. It hurts being so restricted purely because of where you’re born.

Who are some makers you look up to?

Jerry Ellsworth! She is awesome. She taught me to not see failure as a bad thing but as an opportunity for learning. A failure is a huge source of data. I’m not sure how to describe it but there’s so much you can learn from them, she also does insanely awesome stuff, it felt nice seeing such an awesome maker that’s also a woman. I felt really weird about seeing a majority of the community being men, but seeing Jerry helped me feel nicer about it. I also really like the Jubilee tool changer by Joshua Vasquez. 

I just know so many amazing random people around the world that come up with clever ideas. you know, Billie Ruben and RepRyn etc. I don’t know his name but someone with a youtube channel called “Proper Printing” also makes amazing videos! I love his implementation of the tilting extruders. I have to admit his way of making it is a million times better than what I tried. I only would need to attach a motor for faster tool changes and an idler switching mechanism on top to get it to be direct drive. I know this person called Apsu on twitter/discord. She makes awesome printers and all that.

I also love the Voron project and Naomi (SexyCyborg on youtube) and Kate Temkin, I wish I had her brain power! 

Any advice for people reading this?

Never give up! And don’t be scared of failing. The only reason I made my Doot Changer was because I told myself “well, lets fail on purpose!”

I’d also like to remind people that the makers or people they admire aren’t that different then they are. They’re people with flaws and everything like you, so you can definitely be like them.

Oh and don’t be scared of more “professional” stuff. A lot of hobbyist parts and resources are very simplified and hide many awesome stuff. It’s super fine to use hobbyist specific resources but if you ever have the time, you can learn a lot from books and similar resources. I avoided them because I was scared at first. but I realized they are very similar to the hobbyist product/content honestly.

And don’t feel guilty about taking breaks. They’re important. and nobody is creative 24/7. Taking a break is always such a big help, a lot of times I quit a project for a week and come back with a fresh mind thinking “THIS is what I was trying to solve so hard all that time? But it’s so simple!”.

Anything else you want to add?

I really really hope I can one day be in a free country and actually try out many of my ideas. I’m thinking of a far better Doot Changer that I’d make when I’m outside of Iran and have access to a lot of different parts! Even a simple screw can be a pain to find in certain sizes where I live.

The Tool changer’s carriage; one of the cost reductions come from the 3d printed T_Locking bar (I don’t know the actual name, that’s what I call it). The Z axis really needs a re-design tho! The switch on the bottom acts as a very reliable and accurate probe, thanks to the nature of a tool changer you get a free contact based probe on every tool changer :) The XY joiners and the motion system is going to be steel-reinforced soon after it’s out of beta. that’d massively increase rigidity!

This is my version of a “wedge” It basically pulls the tool closer to the carriage the more you spin the T-BAR. like a very spread out large screw that only turns half a turn! They’re also modular so you can screw them in like that. The coupling uses 4mm dowel pins for now, i’ll change them to 3mm once they’re back in stock for weight reduction. I can’t find 1.5mm dowel pins in Iran otherwise i’d use 4 of those inside the wedge for more durability and a stronger lock, right now it’s using two 3mm ones. The disadvantage is a that the contact point is a line and a dot, which strains everything and increases wear, the 1.5mm dowel pin would solve this issue. it’s also much larger, then again I could use the jubilee wedges here potentially if things don’t work out, since the jubilee is popular now the wedges can be had for $2 each, I’d need to slim down the T-bar for it to work somehow though. The wedge for jubilee:

An older version of the wedge, the slots are for dowel pins, they’re inserted at an angle. For now it provides a maximum of 1mm of lift. I plan to make it 1.5mm since it seems to be the sweet spot between torque and ease of use, a smaller lift means the distance between the carriage and tool need to be calculated more precisely. The two stoppers on the top and bottom mean that the t-bar cannot spin too far without breaking those, this means that I can brute force my way into accurate positioning, this has allowed me to use a sensorless DC motor for tool locking. I simply spin the motor until it’s stalled (high current lets me know that it’s stalled) and stop it there, same for locking, once it’s locked it gets stalled and I turn it off. for steppers this acts as a safety feature! I’m planning to reduce its size since it makes me lose some print area on the Y axis.

This is the T-Bar’s gear/spring combined into one part. The spiral spring makes tuning the profile easier since the stopping point isn’t very strict anymore, if you turn the lock too far the spring will let it spin without hurting anything. The gear ratio for now is 2.6:1 for the 28byj but that motor is less than ideal.

My workshop is my room! This makes it hard to work and hard to sleep in, I can’t print overnight which is a huge bummer! but i’m grateful for all of my amazing tools. And i’m extremely grateful for the VR headset! saved years for it :) bought it secondhand!

I’m also extremely grateful for my PC. I bought it right before the inflation spike and before the GPU shortage. I bought this PC for 20 million tomans and right now it costs around 60 million tomans! It was very smart of me :) My monitor is also fancy! I bought it before the inflation got really bad around 6 years ago. Same with my keyboard and mouse and all that! I’m very happy I get to have such a nice PC :) And I was lucky I got it just before things went horrible in Iran. Right now I can’t even buy the cheapest monitor! Oh and on the bottom right there’s my 3d printed trashcan with a 1mm nozzle :)

This one was done on the v1.6! One of the first proper dual color ones. It came out great! There’s some slight artifacting, which I thankfully solved. You can also see some failed prints that I kept.

My printer

A print off my printer. it came out well! I need to add a camera for automatic nozzle calibration



Mike Senese is the Executive Editor of Make: magazine. He is also a TV host, starring in various engineering and science shows for Discovery Channel, including Punkin Chunkin, How Stuff Works, and Catch It Keep It.

An avid maker, Mike spends his spare time tinkering with electronics, doing amateur woodworking, and attempting to cook the perfect pizza.

View more articles by Mike Senese