Hi guys. This here is a homemade, 3D printed and Arduino based Halloween skull. I’ve
designed it in such a way that the jaw will move with a servo motor, we have RGB LEDs
behind the eyes and also below the jaw, it has a speaker inside and it can play scary
sounds, it can detect movement with a PIR sensor that we have here on the head and the
most interesting part, inside it has a homemade mini smoke machine and I will also show you
how to make that. So let me give it a test and then stick till the end, because I will
show you step by step how to make this. I flip the switch and we can hear the welcome
sound and then once it detects movement it will make scary noises, blink the LEDs, move
its jaw and also create smoke just below here. Let me flip the switch.
So what do you think, pretty cool right? So, let’s get started.
What’s up my friends. Welcome back.
We are around Halloween days and I want to make another cool project. Remember that last year
we had a 3D printed pumpkin that was able to play sounds and was creating water mish
out of its mouth together with some addressable LEDs. This time I want to make a scary 3D
printed skull. I’ve made this design so you could easily 3D print it, and then it
would have a moving jaw that you could control with a servo motor. The design has a space
here for a micro 9g servo to move the jaw. The eyes holes have spaces for some LEDs that
we could also control with an Arduino for example. Inside I have enough space to add
a battery, an Arduino a DF player and a speaker to be able to play some scary sounds. But
the best part of this project is a homemade mini smoke machine. You see, water mist is
cool but sometimes you can barely see it. That’s why, for this Halloween I’m making
my own mini smoke machine so stay tuned till the end to see how to make it and how cheap
are the parts that we need. So let’s start with the components for the project. First
of all, we need the 3D printed skull so download my designs from below and 3D print it. Is
made out of 3 main parts. The jaw, the bottom part of the skull and the top part. You have
to print all of the parts using supports because none of them is flat and they all have round
shapes. All this inside the skull is actually support for the 3D printing process. Everything
was printed with PLA material, 0.4mm nozzle and 0.2mm layer height and 20% infill and
2 perimeters. As you can see one was printed with two colors and that’s because while
I was printing it, which by the way, it was around 30 hours of printing time, I was running
out of grey filament so I had to pause the print and continue with gold color. Luckily,
I have a filament sensor and pause mode on my printer. They had a lot a lot of supports,
actually half of the filament it seems to be for supports. Now we have to remove the
supports. For the jaw and the top part of the skull, that was easy. But the middle part
has a lot of supports. So carefully remove everything from the inside and all the small
holes. It took me a while to get it all out. Look how much support material we had inside.
Also be careful because I don’t know how, but I was able to cut myself with one of this
sharp support material. Anyway, now all parts are clean, more or less. Finally, you should
sandpaper all the parts, especially where we had supports, so we had a smoother finish.
I passed two levels of sandpaper and they look better now. In order to have the same
color, I will use some spray paint and give it a few layers of paint. So apply one or
more layers of paint, in my case I will use this grey primer and see if later it would
also need some paint. Once it is dry, I sandpaper the parts again and I then add another layer
of paint. And finally, once the parts are fully dry I might use some acrylic paint and
add some shadow and details. Let the paint dry and till then let’s see what else we
need for this project. I will use an Arduino as always. To move the jaw, I will use a servo
motor like this one, a micro 9G. For the LEDs I might use some 5mm red LED or maybe we can
use some addressable RGB LEDs like these ones here. To create sounds, as always, we can
use a DF player with a micro-SD card and palace some mp3 files on it. This is very easy to
control with the Arduino. It has enough power for an 8-ohm speaker like this one so we also
need this. To supply everything, I’m planning to use a 1S battery of 3.8V so we will need
a voltage booster in order to get 5V for the digital part and for that I will use a boost
converter module like this one with enough current output. And to protect and recharge
the battery I will use this protection module with USB connector for charging. And yes,
the battery is from a smartphone because I have a lot of these batteries and I need to
reuse them. We also want to make the skull react to movement so for that I will use a
PIR sensor like this one here. And now for the cool part of the project, what we need
for the mini smoke machine. Well, I want to use the heating element of a vaping cigarette.
I’ve bought a few models and see which one is best, so stay till the end to see that.
To push the smoke out we need some sort of pump and I will try to get mine out of an
aquarium air pump that I don’t use anymore, and if it doesn’t work because it is using
high voltage, I will have to build one myself since the one I’ve ordered some days ago
hasn’t arrived yet. Or maybe I will just use a fan to push out the smoke. We also need
some smoke liquid. I have some from my previous huge smoke machine and if you want to see
how I’ve made that, check the video in the description. Anyway, to make sure it is compatible,
I’ve also ordered some vaping liquid, with menthol flavor. To control the power of the
heater and the pump we will need two MOSFETs which we can control with the Arduino. That’s
pretty much all we need and if I use any other small part, I will put it in the full part
list on electronoobs.com and as always you have all the links below. So, let’s start.
First thing first is to prepare the skull which by now should be dry and have a nice
grey color. We might paint it more later with details and shadows, but for now, it is good
like this. First, we must add the servo motor in place, otherwise, once we have the jaw
mounted it would be more difficult. So first we add some insertion threads as always using
my soldering iron. Now pass the wires inside the skull and fix the servo in place. Then
add and tight the screws. The servo is in place and we have the wires inside the skull.
Now we can add the jaw. Slide it inside of those two holes. Then I add a screw, but I
had to use some glue to fix it in place, because there was no more space for a screw nut. I
guess I’ve made a bad design choice. Anyway, glued in place it will be ok as well. To fix
in place the top part I thought of using magnets. So, we have these slots all around the skull.
We have to add a neodymium magnet on each slot except these two holes. So, I use some
super glue and add a magnet on each hole but make sure that the ones on the bottom side
have opposite polarity than the ones on the top side so they will attract each other.
Now that we have the magnets, look how easy is to close it. The plastic part is ready.
Let’s pass to the electronics but before we make connections, let’s make the mini
smoke machine. First, I have to open the aquarium air pump and see if I can use it. After I’ve
opened it I realize it is just a 220V AC pump made with a transformer that’s moving a
rubber membrane, so I don’t think I can use it. I’ve taken the pump out so I think
I could use it if I add a DC motor that would push the membrane very fast. But since that
would vibrate a lot and make a lot of sound, I’ve decided to test first the 12V fan I
have. I fill the first pipe with some smoke liquid. The idea is to connect power to the
heating element inside of these vaping pipes. The heating element is just a resistive wire
and is inside here and is something like this. That will heat the liquid and create the smoke
and I will use the fan to push it out. The design also has a small hole here below the
jaw, so the smoke should exit there. I solder wires to positive and negative connections
of the heater. Then I make a bigger hole on the side and this is where the air should
enter and push the smoke on the other side. Now I should make something that should hold
the fan like this and also push the air towards that hole I’ve just made. That’s why I’ve
3D printed this part here. Then I glued the vaper pipe inside and made sure air could
flow to that hole on the side. Then I screw in place the fan and I hope this will work.
I supply the fan and then I connect the heater. The smoke is coming out, but not as hard as
I was expecting. The fan is not powerful to create enough pressure. That’s why I’ve
remove the vaper from the 3D printed part and I will use this other one. This has a
more direct hole. I solder wires to the heating element as before. I now glue it inside the
3D printed part. Then I add the fan and let’s test this one as well. This time the smoke
flows a lot better and I’m happy with the results. But the fans needs 12V so I will
use another separate boost converter to increase the battery voltage up to 12V just for the
fan. So, we can assemble the rest. This should be the schematic for this project so check
the final one below in the description in case I change something till the end. I glue
the boost converter to the smoke machine and I solder the wires and make sure I set the
output to 12V. Then I also add the MOSFETs we use to control when the smoke and the fan
are turned on. I solder the Arduino and the DF player on a prototyping PCB. I solder the
speaker at the DF player output. I also add a switch on the back of the skull and this
will be connected to the battery and the 5V boost converter. I connect the protection
and charger module to the battery. I also solder wires to the PIR sensor and the addressable
LEDs. Everything is now prepared just as in the schematic. So, I will glue them inside
the skull and make the connections. First, I connect the 5V boost converter to the switch
and glue it inside the skull. Then I also add the battery with the charger and glue
them in place. Then I add the smoke machine module on the hole the 3D printed skull has
on the bottom. Then I glue one LED inside each eye. Finally, I glue the Arduino and
DFPLAYER PCB on the other side. We can make all connections here at this point. On the
other 3D printed part, I’ve made a hole and glued in place the PIR sensor that will
detect movement. I add wires with male pins so we could connect them to the wires on the
other 3D printed part and be able to close and open the skull. I also glue the speaker
in place, and I had to make a few holes on the back so the sound could exit. I will have
to repaint this part. I finally decided to add another LED below the jaw so we could
light it up and like that the smoke will be more visible. I get the SD card and upload
the mp3 files to it. Then I insert it into the DFPLAYER. Now the skull is ready for the
code so download it from below together with the needed library and upload it to the Arduino
NANO. The code is more than easy. Here we detect if the PIR sensor is active. If yes,
we activate this “movement detected” variable. While this is active, we make a loop where
we play a scary sound and we blink the eyes LEDs with red color. We also move the jaw
with the servo. When 9 seconds have passed, we reset the “movement detected” variable
and it will wait again to detect movement. That’s it for the code. To move the jaw,
we must connect the servo to the plastic part. For that I will use some metal wire. Bend
it and connect it to the servo in such a way that it will push and pull the jaw. The scary
skull is ready for the first test, so let me close the top part and give it a run. By
the way I’ve also 3D printed this support, so the skull will stay straight and not touch
the table with the jaw. Flip the switch on the back. The welcome sound will play.
Now when I move, this happens.
We can hear an evil laugh and the eyes LED are blinking.
For 3 seconds smoke will come out from below the jaw. You can see here how smoke is coming
out so the mini smoke machine is working perfectly. Also, the bottom LED will turn white so we
can better see the smoke. And on top of that the jaw will move up and down. Pretty cool,
right? Finally, I’ve decided to use some acrylic paint and add some shadows and details.
A bit around the eyes, between the teeth and some extra shadows and it looks like it was
a bit dirty. Now it looks better, right? SLOW. So guys, that’s how I’ve made my own automatic
scary skull with a smoke machine, moving parts, scary sounds and flashing lights. You can
easily open it with the magnet system. Then plug a USB cable and charge the battery. I
hope that you like my design. You have everything below ready for download. If you have learned
something new, consider giving me a like or comment below. Happy and scary Halloween.
Thanks again and see you later guys.