Introduction: Star Wars Thermal Detonator 3d Printed

Picture of Star Wars Thermal Detonator 3d Printed
The mighty Jabba asks why he must pay fifty thousand.
Because he's holding a thermal detonator!

With Star Wars day fast approaching I felt it was only appropriate that my next project was a Star Wars one. I figured that the thermal detonator was the way to go.

There are quite a few examples of replica thermal detonators out there as well as the official Lucasfilm licensed master replicas props, but I've not come across any instructables for one yet, so I've happily obliged.

I used a 3d model created by Oubliette as the basis for my detonator, it's a good quality model that prints well and assembles nicely, the model is available on Thingiverse, also be sure to check out Oubliette's website.

This instructable covers the 3d printing of the prop, the painting (including a handy weathering technique) and the electronics to generate the lights and sounds of the prop.

May the 4th be with you

Step 1: The 3d Printed Parts

Picture of The 3d Printed Parts

The first thing we need are the 3d printed parts, the ones we are using were designed by The Oubliette. The STL file is included here and is also available on Thingiverse.

I printed mine using the following settings on a XYZ DaVinci 1.0:

  • Infill: 90%
  • Layer height: 0.1
  • Supports: Yes medium density
  • Speed: Standard
  • Shells: Normal

Once you've printed the pieces you'll want to check everything fits, if you find things are a little tight you may want to sand the areas where the different parts meet. Remember that if things are tight now, they'll be even tighter once you've put a few coats of paint on.

Tip: If you don't have access to a 3d printer, you can use 3d printing services such as 3d Hubs and Shapeways.

Step 2: Painting and Weathering

Picture of Painting and Weathering

Paint Preparations

To paint the Thermal Detonator and apply the weathering effect, you'll need the following colours:

  • Metallic Brass / Gold
  • Brilliant Metallic Silver
  • Matt Black

To create the weathering effect, you'll need the following additional items:

  • Salt
  • Water
  • Small paint brush for applying water
  • Clean and dry toothbrush

Lightly sand the 3d printed parts with a fine sandpaper (P120) to smooth prior to painting, taking care to remove any dust with a tack cloth. I then primed the pieces using an all surface primer and left to dry for a few hours. The top slide switch grip piece is then painted in the matt black.

First Coat of Colour and Paint Weathering

To create the weathering effect we will first paint the main detonator parts using what will be the rust / corrosion colour. Spray the top section, bottom section and main slider piece in the gold / brass. I did a coat of the metallic brass, then after allowing a few hours to dry I followed this up with a coat of metallic gold, immediately followed by another coat of the brass. You will want to want to allow this 24 hours to dry as the paint needs to be 100% dry before the next stage.

The weathering effect will be achieved by using the salt and water. Using a paint brush apply water to the areas that you want to have signs of corrosion, you'll want to focus on areas where moisture and dirt would naturally collect (such as in and around grooves).

Take the salt and sprinkle it over the thermal detonator, you'll find that the salt will stick to the wet spots and begin to crystallise. Once you've covered the wet areas in salt you'll want to leave it for at least an hour to let the salt dry thoroughly.

Once dry you can gently blow off the loose bits of salt, you can then spray paint the rest of the thermal detonator in the final colour. I opted to use a brilliant metallic silver. Allow another 24 hours for the paint to thoroughly dry.

Now comes the fun part, using the toothbrush you can remove the crystallised salt to reveal the corrosion, this should leave you with a fairly good weathering effect. Test fit the assembly again, you'll want to make sure the paint hasn't stopped things from fitting together nicely.

Step 3: Intro to the Electronics

Picture of Intro to the Electronics

Using lighting and sound on a prop really adds that extra dimension and brings things to life, the thermal detonator is no exception.

To re-create the light effects we will be utilising the following items:

To re-create the sound effects we will be utilising the following items:

Alternatively Adafruit also have a combined sound board and amp, though stock is limited as I believe the item may have been discontinued.

The whole thing is powered using a 4.5v battery source, I used 3x AAA batteries for testing purposes and these are replaced with 3x N batteries in the final assembly to save space.

Experimental: I've included some PCB design files for the circuit. One design is intended to use serial communication with the soundboard to trigger sounds, the other uses the GPIO based triggers. It also includes a tilt switch and a DIP switch to give more functionality. More info to follow once I get the chance to build and test...

Step 4: Lighting and Sounds

Picture of Lighting and Sounds

Circuit Assmebly

The circuit is assembled as per the schematic provided. The on/off switching is achieved using the roller switch. When the top slider is slid back to reveal the red LED, the roller switch opens. This closes the circuit, activating the lights and triggering the sounds.


You'll find that the batteries are one of the more troublesome aspects of the build. You'll need something small enough to actually fit inside the Detonator enclsoure, but also large enough to operate the electronics for a suitable length of time.

AA and AAA batteries are too large to fit inside the enclosure, so I opted for the smaller N batteries. I recommend using a battery holder like the one shown in the photos as it will make changing flat batteries easier. But as I was in a hurry, I soldered my wires directly to the batteries.

Flashing Light Sequence and the PICAXE

The yellow flashing lights on the front of the detonator are designed to replicate the pattern and timing of the movie prop. It only appears on-screen in ROTJ for a few seconds so the start of the light pattern is replicated from the movie scenes, the rest of the pattern is taken from the Master Replicas prop. This light sequence is achieved by using a PICAXE microcontroller, the code I used to program the chip is provided below. I happened to have a spare 18 pin PICAXE to hand so I used that in my build, but to save space I'd recommend you use an 8 pin chip instead. The code below is intended for a PICAXE-08M2 wired as indicated by the circuit diagram.

high c.0
low c.1
low c.2
pause 2000
high c.0
high c.1
low c.2
pause 2000
high c.0
low c.1
high c.2
pause 2000
low c.0
high c.1
high c.2
pause 2000
low c.0
high c.1
low c.2
pause 2000
low c.0
low c.1
high c.2
pause 2000
high c.0
high c.1
low c.2
pause 2000
low c.0
high c.1
high c.2
pause 2000
goto main


The Adafruit soundboard is surprisingly easy to program. Triggers are set by simply naming the audio file, using a file name format that corresponds to the relevant trigger switch. For more information follow the tutorial on Adafruit. I've only utilised the main detonator sound effect, but it is also possible to add additional effects (i.e. detonator explosion when the prop is shaken) through the addition of tilt switches etc.

As an alternative to the adafruit sound board you could also use a PlecterLabs board that's pre-loaded with a Thermal Detonator sound font that includes various other effects and features.


The most complicated part of final assembly is actually getting everything to fit, be as conservative as possible with cable lengths when soldering everything together, you want to minimise unnecessary usage of space as it gets very tight in there! You'll see fromt he photos that I wasn't particularly neat and my strip/vero board is quite large, but even so everything fits.

I placed the components into my detonator enclosure in the following order:

  • Amp at the bottom - it is the narrowest so it can sit nearer the base of the curve
  • Soundboard next
  • Then the custom built circuit - as it is the largest
  • The batteries next - all of these should sit just around the height of the three yellow LEDs
  • The speaker goes next - you'll see that my speaker is actually quite chunky, a smaller one would fit even better

This should conclude your build, I hope you enjoyed the Instructable.

Note: that I have not included the thermal detonator sound effect audio file as part of this instructable as I am unsure of the copyright status. I believe it was taken from a Master Replicas thermal detonator prop that was created under license from Lucasfilm so I am not able to re-distribute it openly :( If you turn to Google you should find some sound effects you can use.


Dirt Devil (author)2017-04-27

Can anyone recommend parts available in the U.S. (like Amazon) that fit for the roller switch, red LED and the speaker? It's hard to tell the size of the parts used from the photos. Thanks!

Newark in the US have the exact same red LED, Amazon used to have a seller that provided it but not anymore.

This is the roller switch on RS Components in the UK, you're pretty much looking for any microswitch that has a roller lever.

As for the speaker I used this one, it's 8ohm, 2watt and measures 50mm diameter by 17mm high. I'd recommend you look for something a little slimmer though, it will make it a lot easier to assemble! Just make sure it's rated to work with your amp/soundboard.

Thank you kindly for the info. This looked like such a fun project I couldn't resist!

In one of the parts photos laid out on the table, there are 2 black plastic parts, possibly 3D printed, wondered what those are?

Also wondered if you might have a photo of all the parts installed into the shell halves that you could share?

No problem, hope it helped!

I forgot those 2 plastic parts were in the photo, they were originally designed to mount a couple of the boards/circuits, but it got too cramped inside so I had to ditch the idea and just put the bits in loose. So they were not actually used.

Apart from the roller switch and the red LED being hot-melt glued in place, everything else is just kinda crammed in to be honest. But once I'm finished with the project I'm currently working on I'll update this I'ble to include some more detailed steps and photos of the internals. I'll also be publishing a PCB design that can be etched instead of having to use vero/strip board, this will make things a lot more compact inside.

Thanks TED, those sound like super additions to an already-great l'ble. I look forward to seeing what you'll come up with.

I've got around to taking photos of my assembled internals, I've also added some extra info about the assembly process and the batteries to the Instructable.

Hopefully this info will help, I'll be starting the PCB design this weekend so will have more updates coming soon.

Thanks for adding more info, will definitely help. I'm still gathering parts and still have more sanding of the model to do, so I'll be able to take advantage of anything you add.

Dirt Devil (author)Dirt Devil2017-10-06

Hi, just checking in to see if you are still considering working on a PCB for this project.

Yes that is the intention. I have started to design the PCB (I've added the untested experimental designs to the Instructable). It's just a matter of finding the time for me to build and test the new design before updating the Instructable to include the new steps.

BlackyB06 (author)2017-08-05


I have troubles with the flashing light sequence, I can't make it works and I don't know what I'm doing wrong

I'm totally new to the electronic world but I tried to replicate what you did (I don't get what's the point of the 100nf capacitor)

I had troubles programming the Picaxe but it should be okay by now, I used the official AXE027 cable and pasted your code

First thing you can check is that the code works when you simulate it in the PICAXE Editor. The code I've provided should work on all versions of the 8-pin PICAXE chip.

The next thing is to check your circuit. If you're new to PICAXE check out their Getting Started guides, they're really helpful.

The 100nf cap is a decoupling capacitor and all ICs should have one. It suppresses high-frequency noise in power supply signals, it basically protects the PICAXE chip. This capacitor should connect between the power source (V+) and ground (V-) as close to the PICAXE power pins as possible. The attached image shows its ideal location on your breadboard.

Does anything else looks suspicious to you in my circuit ?

I don't know what is supposed to happen when I 'simulta' in the editor, nothing particular shows up

Everything else looks ok as far as I can tell. I can't quite see the colour bands on the resistors to check their values though, so make sure you are using the correct ones. If in doubt you can use this resistor colour code calculator.

With regards to the simulation in the PICAXE software, copy and paste the code into the Editor, then do the following (I've included a screenshot to illustrate):-
1. Click the 'Simulate' tab.
2. Click the 'Run' button (if it produces an error, check you copied the code correctly).
3. As the code simulation runs, it will highlight the active code line in yellow.
4. The pins of the PICAXE chip will change colour to indicate their status, the green indicates output. This represents the LED switching on.

I tried just now and it works in the Picaxe Programm

That means the code is ok, it's probably worth re-programming the chip just to make sure everything is hunky dory and there are no errors, you should get a clear indication that the program downloaded to the PICAXE successfully.

Now it's just about the circuit, make sure the 100nf cap is in the right place and double check your resistors are the correct values.

RichardB432 made it! (author)2017-05-10

I'm having power troubles with mine. I've put 3 x 1.5v watch batteries together (as space is a SERIOUS problem) and it works for a while then doesn't play properly. I've kept checking that the connections are ok but keep getting this problem. I put 4 batteries together and then the same thing happens again!! Can you advise why this may be happening? Are they not powerful enough?

I suspect that the problem is the batteries and they are not up to the job. While values differ by battery type, the average watch battery has a capacity of around 50mAh. The soundboard and amp are a fairly big power drain and will probably need something closer to at least 500mAh to get everything working properly.

AA and AAA are out of the question due to their size, but I managed to get 3x N batteries to fit in my detonator. They provide something like 850-1000mAh and I still have the same original batteries in my TD as I did when I first built it over a year ago (and they still work).

I think you'll get N batteries in there from looking at the photo, but you probably won't get all three in a complete battery holder. My three are wired in series (to get 4.5v output) but they are placed in the TD individually. I'll try to take a photo of the inside of my TD and add it to the I'ble later, I've already been asked to do so by somebody else as well so probably about time I did.

To test that it is your batteries causing the issue you could run it with AA batteries outside of the enclosure just to prove that it works.

I've done that already and it's much stronger with the 3 x AA's powering it, so I kind of thought it was a battery issue. N batteries look like they are gonna cause me major space issues which is a worry. I'd say each one of those is the size of the 3 watch batteries I had together!

I've added some photos of my internals, hopefully this will help you make sense of how mine fits together. I've also added some extra info to the Instructable regarding the batteries as well as some advice on getting the circuits to fit.

Looks like you've done a far better job of squeezing everything in. I wasn't confident in my board so I soldered those connecting pin things in but they take up much more space and I'm regreting it now. I've also hot glued around soldering joints to avoid them snapping with all the forcing in I'm doing but as they don't bend well it's making things even tighter. I'll try those batteries. Can you solder to them? I tried soldering to those tiny batteries but it just slides off? I think I'm just going to have to squeeze them in where I can and hope I can get it to close!! If not, it's back to the drawing board

You'll find that due to their smooth shiny surfaces the solder won't bond. You'll need to roughen up the areas your're soldering to by lightly sanding or filing them first.

I've finally finished a couple of other Instructables I've been working on (the Working Pokemon Poke Ball and a 3d Printed Light Saber) so I will have a chance to make some 'proper' electronics for the Thermal Detonator now. I'll be designing a custom PCB and adding better controls of the sound effects. Hopefully it won't take me too long to get this done and published, so at least if it is back to the drawing board, you might end up with something better.

RichardB432 made it! (author)2017-05-10

I'm having power troubles with mine. I've put 3 x 1.5v watch batteries together (as space is a SERIOUS problem) and it works for a while then doesn't play properly. I've kept checking that the connections are ok but keep getting this problem. I put 4 batteries together and then the same thing happens again!! Can you advise why this may be happening? Are they not powerful enough?

RichardB432 (author)2017-04-01

Hi there,

I've got the 8 pin chip instead of the 18 pin chip you used. How do I know what goes where on a circuit board though when I wire it up as it won't be connected to the same legs (not sure the right term) of the chip? I'm buying a cable to program the chip as it's not cost effective to make it. I can get a cable for £5!

If you check the schematic for the 8 pin chip you need to wire the LED's to any 3 output pins (amend the code relative to the pin number changes), from memory the V+, GND and reset pin (the one with the 4k7 resistor) are the same.

That honestly means nothing to me! I'm trying so hard to get my head around this. I can see the 4k7 pin is 4, VDD & GND look like they are linked to all the yellow LED pins and pin 14? How does that relate to your code as these pin numbers aren't referenced in your code? On the schematic why do some lines not have a dot? I'd assume that means they don't connect but why join them? Does it mean it's a jumper wire?

The schematic was a little confusing as it was missing a couple of the dots to indicate where a connection is made at a cross-section, hopefully it will make a little more sense now I've tweaked it a bit.

Where a line crosses over another line at 90 degrees to each other they are not connected. Cross sections are only connected if there is a dot to indicate as much.

So the yellow LED pins connect only to the PICAXE chip on one side, and to ground via a resistor on the other (they are not tied to the VDD and ground).

I'll make a new shematic on the weekend that's clearer, I'll also post some information that's specific to the pin-outs of the 8-pin chip.

That would be amazing! I've nearly got the sound file going. I've used a music program and over-layed some jabba etc to my detonator loop. Having problems with a long loop though as it makes the file size too big as a wav file. That updated schematic really helps

I've changed the Instructable so it's specific to the 8-pin chip, this includes changes to the parts list, the schematic and the code. It should make more sense now.

One thing I failed to realise during our previous discussions is that the 4k7 resistor is only relevant for PICAXE chips that have a reset pin. In the case of the 08M2 chip there is no reset pin so forget about the 4k7. You will however need a 10ohm resistor to tie pin C5 to ground (as indicated in the schematic).

That's brilliant thank you so much, I'll give it all a try. Hopefully I'll have something working on a breadboard soon. I went the breadboard route in the end. It helps a novice get his head around things. I see why they exist now

No problem, hope it helps! I tend to breadboard everything when creating a new circuit, helps to find problems in my design before actually soldering stuff together. Really handy bits of kit.

I'VE DONE IT!!!! Sound isn't perfect but it works. I don't think I can get it to work like you have it. It will play the first sound on a pin and the main loop on another. Sound didn't work at first when I added it to the breadboard but I think it was where it was in the main circuit. If you see what I mean. I put the switch nearer the sound board on the circuit and it worked!! I think it's all been more luck than judgement!!

RichardB432 (author)RichardB4322017-04-22

I'm not looking forward to actually trying to make the real thing now!!! It's going to be tough!! I'd like to post a video of the working breadboard but not sure I can

RichardB432 (author)2017-04-01

it also has to play the final 'turn off' sound when you turn it off which is the last part of the sound file!

The turn off sound is optional, it gets a bit fidgety to execute as it requires the thermal detonator to be powered up all of the time. The off sound triggers when the roller switch is opened/closed after the loop section. In my upcoming update to the Instructable I'm including a circuit where the audio is triggered by the PICAXE and not solely by mechanical switches and the circuit.

I'll have a play with it and see what I can stumble across. It's a shame you can't just have a trigger that is programmed with a 'start' sound, 'loop' and 'off' sound. You could then trim the wav file down to play each part.

RichardB432 (author)2017-04-01

just looking at downloading the sound file onto the FX board. How do you get it to loop the sound until it is switched off? Also the looping has to restart from after the 'switching on sound' doesn't it?

You can either experiment with the triggers on the soundboard to play the switch on sound then the loop section, or for simplicity you can edit the audio file to play a single sound file that includes the switch on sound then a really really long loop section so it never reaches the end of the audio file unless you have it switched on for a really long time.

RichardB432 (author)2017-03-15

Hi there, can I program the chip with Arduino Uno as I have one of those?


If your question is whether a PICAXE chip can be programmed with an Arduino Uno then I believe the answer is no, as the Uno does not have an FTDI chip. The PICAXE can be programmed with an Arduino FTDI cable though, as long as you are also using a hex converter (the signals on the Arduino FTDI cable are inverted compared to the PICAXE). Read more about this here:

It will probably be easier just to build your own PICAXE programmer, this is quite simple if your computer has a serial port, there's an Instructable for this:

If you want to use an Arduino in place of a PICAXE then you can use your Arduino to program an ATMega chip and use this in the thermal detonator instead, assuming you can get all the components to fit afterwards.

Firstly, thanks so much for getting back!

I've programmed an Atmega chip before for my Boba Fett chest display so this may be easier for me as I looked at that tutorial you gave me and it went over my head to be honest. Am I right in saying the program code will be different though? Also what ATmega chip would I need? The wiring up I guess would just be the same just the programming?

These things always seem simple at first but then in reality (not being an electronics whiz) there is a lot more to it!!!

No problem, will always try to help if I can. The Arduino and PICAXE code is different (PICAXE is programmed using the BASIC language) so you will need to re-write it. I'm not very proficient in Arduino, it's something I've only recently started tinkering with for a new project I'm working on so I'm not going to be much help there.

There are quite a few Instructables on programming ATMega328 chips, my only concern is whether the ATMega328 chip will be compact enough to fit in the thermal detonator housing.

Is this the cable I would need to plug into the computer to program the PICAXE chip? See below..

If so, how do I plug the chip into the cable? Could I build your board/circuit with all the parts and then somehow plug it into the computer via the cable and program it (with relevant software)? I know I look/sound daft, I really don't know what I'm doing!!!

FTDI USB to serial PicAxe download programming cable 3.5mm jack

No worries, the cable is basically a USB to Serial adapter, there's a few other minor components necessary to get your PICAXE ready for programming, but a number of starter kits are available direct from the PICAXE store, see the following link:

With regards to the software required, PICAXE provide this for free and it can be downloaded from here: this software enables you to simulate the PICAXE, allowing you to test your code before trying it on the real thing.

If you're considering getting started with PICAXE, they also provide a pretty good set of manuals here:

There's also an Instructable showing just how easy it is to build your own PICAXE programmer for use with the USB cable.

It does look easy to build it but then wouldn't I need to put the chip on a breadboard and program it? Would it be easier to for me to buy a starter pack where you put the chip on the board/kit provided and then program it that way? Then just put your example together? I just think the less I have to do the better!!! Less chance of a mistake! Thanks so much for your help!

You can place a PICAXE chip on a breadboard and program it there, you just need a few minor components, the TFDI cable and a 3.5mm jack. Purchasing a starter kit is probably easier, but breadboarding the download/programmer circuit is probably cheaper. If you want to build the download circuit yourself you'll need the following items:

1x PICAXE 08M2 Chip
1x 100nF capacitor
1x 22k resistor
1x 10k resistor
3x AA batteries and battery box
1x USB FTDI Cable
1x 3.5mm PCB mounting socket

The attached pictures show the pin-layout of the chip, the schemtic to build the download circuit and a diagram that shows how the pins on a typical 3.5mm socket correlate to the PICAXE. These diagrams are taken from the PICAXE Getting Started manual.

Note that when programming is complete, your final circuit must be tied high by connecting it to the V+ via a 10k or 4k7 resistor.

On your Thermal Detonator are you just adding the light effect or will you also be adding the sound as well?

I will be adding the sound yes and that bit does look far more simple! Just downloading some sounds to the triggers? Thanks for the info. It all seems like building something to program a chip though is an added problem to solve as I really don't understand it all. I ordered my last board that was all linked up with soldered lines and words telling you where resistors go etc. Not sure how you describe it. and I just had to copy how someone had soldered everything (with the addition of programming the chip). If I built your board could I link a starter kit to it and program the chip that way or can I just plug it into the starter kit and put the code onto it? If I build the board to program it wrong then I will end up in a right mess and may never end up with something that works at all!! haha....sorry for all the questions. You have been very patient!!

Yes the sound board is simpler as it's an off the shelf item, just some minor soldering to be done, then copy the sound files to it just like a USB flash drive.

With regards to the PICAXE, I think the real question here is are you likely to take what you learn from the experience of making it and apply this knowledge to a future build/project, or do you think it will be a one-off solely for a thermal detonator?

That is very much the important question and info I should have perhaps gave you from the start! My apologies.....

I really just want to make the detonator for now.

Apologies for the delay in reply, I saw your previous comment regarding the parts list (you must have deleted the comment since). I only managed a quick look at it (the link is no longer valid) but I recall you had a 47k resistor on the list, this should be a 4k7 (4.7k). I didn't have a chance to check the other components in any real detail, but apart from the resistor nothing stood out as being wrong.

The other thing worth mentioning is that in the final build I used N batteries instead of AA's, they are the same voltage (1.5v) but around half the length, so they are much easier to get them to fit (this is noted in the I'ble).

That's strange? I can see my comment with the link and it still works?

Anyway, I'll get that list ordered and the other resistor instead. I thought it was a typo as I couldn't find anything on a 4K7 resistor. I'll surely be in touch when I start the build! Possibly the programming as well!! I can't see it going 100% smoothly without any problems


About This Instructable




Bio: I work as an I.T. Support Technician for my 9 to 5, but my true passion is designing, engineering and making. I mostly work ... More »
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