Thermal Detonator - Accurate 3D model and resin build (picture and info heavy)


Well-Known Member
Hello all,

My last project was a screen accurate floating Jedi Training Remote, and having built a spherical Star Wars prop replica using my resin 3D printer, I was hungry for more, so I decided to tackle the Thermal Detonator held by Princess Leia in Boushh disguise in Jabba's Palace next.


I found this model by Roel Veldhuyzen on Thingiverse and printed a copy on my Phrozen Sonic Mini 8K printer:

It was pretty accurate to my untrained eye, but after reading a bit more, I realized that the diameter was too big at 7 cm, and the slide switch could be more accurate.
A picture from one of the Star Wars props books I have lists the diameter as 6 cm:

So I resized the same model to 6 cm and printed a new version:

This seemed a tiny bit small to me, and after a bit more research I realized one of the pictures of the worn down original prop showed that the sphere was transparent and showed a bit of the internals, note the white (nylon?) ring probably housing the mechanics, and the blue and purple electrical wire we can see.

Having come from the Jedi Training Remote build where the original prop was all but confirmed to have been constructed using two Plastruct 6" acrylic hemispheres, then it would be plausible that the Thermal Detonator would also be constructed in the same manner. User Spoudastis thought the same in his WIP Thermal Detonator thread, and combining this knowledge with the measurements from the Master Replicas prop provided in this thread measuring the outer diameter to be 63.6 mm, we can conclude with pretty good certainty that 2.5 inch (63.5 mm) Plastruct VHH-250 hemispheres were used.

A side note: The Master Replicas Thermal Detonator was modeled using a prototype made by Adam Savage (of Mythbusters fame). He got to take measurements of the original prop at the Lucasfilm Archives. He tells the story in this video and has a funny anecdote about being called by the FBI during this project at the end of the video.

With this knowledge in mind, as well as the scribed lines on the Roel Veldhuyzen 3D model tapering off towards the top and bottom instead of staying a constant width like the original prop, I set out to 3D model my own Thermal Detonator.

After starting the project back in September it came to a halt when trying to model the thumb switch as it was quite a challenge to get it correct.
I decided to print the top and bottom hemispheres as well as the middle ring just to see how it looked (still using the thumb switch from Roel as a place holder). I also found a red lens cover that was very close to the original (link here).


The three LED holders are printed as separate pieces as they were on the original prop (and for ease of painting I guess).

I couldn't find many different 2 mm LED's for the three center LED's, and the ones I could find were a bit short, so I decided to modify the ring around them to be chamfered so you can see the bulb better.

Upon closer inspection the original seemed to have chamfered rings around the lights as well, but it's not easy to be absolutely sure:

I scoured the web for all reference photos I could find of the original prop in as many orientations as possible and used these as reference for the over all scale and dimensions, but the thumb switch specifically. Using these reference photos coupled with the measurements of the MR one from the linked thread above I got back to the project last week and got very close in accuracy (in my own opinion).

I think my switch even looks a smidge bit better than the Master Replicas one, I feel it's a tiny bit short and the bottom edges are too rounded.

The switch and the rubber tank tread are modeled as two separate pieces, both for ease of painting and if someone wants to print it separately in a flexible material.
I have yet to model anything internally, I will at least model something that limits the thumb switch movement so it slides to the same positions as the original prop, then I'll print a new prototype.

For paint I'm planning on painting it with Alclad Chrome over a gloss black undercoat, I'd also like a weathered version, but I'm not really sure how to go about that. The original looks to be a vacuum metalized chrome where pieces have flaked off and the metal has turned a spotty brown, how much of it is intentional and how much is natural weathering and age is hard to tell. You can tell how it deteriorates over time from picture to picture, and use the amount of "spikes" left on the rubber tank tread on the thumb switch to place the pictures in chronological order.


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Well-Known Member

Yesterday Adam Savage's Tested had a live stream where I asked how the original prop was weathered and Adam himself answered, confirming that the original prop was made from two acrylic Plastruct hemispheres that were vacuum metalized (explaining the process), and then given a weathering pass with an airbrush (which was new information to me, I thought it might have been some acid or other reactive metal treatment), and then a second pass of weathering was of course the prop sitting around for 20+ years in the archives and subsequent world tours on different exhibits where the vacuum metalized coating was chipped off, "making it look even cooler".
He ends the segment saying "those are all the things I know about the Thermal Detonator", hehe.

I'm very happy to have gotten a first hand account from someone intimately familiar with the prop (having handled it to make a replica prototype for Master Replicas as mentioned in my previous post), this makes me more confident in making a chrome version and then trying to add some weathering filter passes with an airbrush to try to match the original prop.
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Well-Known Member
I printed out two new prototypes, (why make one when you can make two!) below are a couple of pictures of one of them.
(Note that I also printed out a temporary base I found on Thingiverse, it looks decent, but I'm not sure the aesthetic meshes with the TD, I might switch it out for something else).



I redid the three LED holders internally so the LEDs could be seated in them, similar to the KR Thermal Detonator kit. I also remembered that I ordered some clear warm white LEDs for this project that has a bit longer bulb, so I took that into account.

I see areas that still can be tweaked, and I have a bit more fine sanding to do before I'll add some paint.

I definitely want to have working lights in the Thermal Detonator(s), but I'm not sure if I should go all out and add sound as well.
On the one hand my day job is doing circuit board design, so I could make a custom board for it, on the other hand I have limited time to work on personal projects, so a finished solution like the Thermal Detonator Sound Board v3 from Plecter Labs is also tempting, although that's out of stock at the moment.
Making a custom board with sound and motion control is it's own project in itself, considering both the hardware and the firmware, and I'm not sure how keen I am on that. Maybe I'll have it as a side project long term.

If you have any input, please comment.


Well-Known Member
A few months ago I was going to try painting the Alclad Chrome on some spare prints, it requires a gloss black undercoat before the chrome is airbrushed on.

I had a hard time getting a smooth glossy finish with the Alclad Black Gloss through the airbrush, I got "orange peel" texture where the coverage wasn't sufficient, runs where I tried to spray a bit more and difficulty finding the sweet spot of coverage. I tried a rattle can with black gloss as an alternative on another print and got similar results with that, so I set them aside, planning to figure it out later.

Yesterday I brought out the one that was sprayed with the rattle can and sanded the top half with 5000 grit, which made it a lot smoother and shiny. Later I applied a bit of the Alclad Chrome to see how it would look and I was pleasantly surprised.
I used this as a test piece to see how different opacities of the Chrome layer over the gloss black would affect the finish, where I kept it light on the back side and more heavy on the front where the red LED will go.


Today I'll try a gloss clear varnish (Vallejo Polyurethane as that's what I have on hand) over it to first of all see if the paints react with each other and then see if the areas with a heavier application of the Chrome will become more shiny (which they should if it works).

Alclad recommend using their own aqua clear gloss, but I don't have that, and would have to order it online paying a hefty premium due to shipping and taxes. Trying out clear varnish I already have seems reasonable. If it doesn't work I'll see if I can get the Alclad clear gloss.

I'll also try lightly airbrushing some burnt umber and black ink over the chrome with and without gloss varnish to protect the chrome finish to see how it works out.

Looking forward to experimenting with this.


Active Member
Wow, nice work!
You went a lot deeper than I did years ago with this model :D
I have been meaning to make this one more accurate and for a while now, but I might not have to if you are planning to make your files available. It looks great so far!


Well-Known Member
Wow, nice work!
You went a lot deeper than I did years ago with this model :D
I have been meaning to make this one more accurate and for a while now, but I might not have to if you are planning to make your files available. It looks great so far!
Thanks a lot!

And thanks for making the original one, I think it still looks great :D
I'll definitely make these files available when I'm happy with them :)


Well-Known Member
I started painting today and was able to lay down base coats on every part. The top and bottom hemispheres got their first coat of Alclad Black Gloss base coat with an airbrush, I'll give them a second one tomorrow.

The middle rings are as good as done I think:


The metal is Vallejo Model Color Dark Aluminum. It was sprayed over a black undercoat and the middle rings was given some light passes of very fine grit sand paper to give it a slightly brushed feel.
A picture of how the LED's are seated on the backside:

The thumb switch and tank tread also got a base coat, I think I'll go in with some gloss over the switch and satin over the tank tread to change the look of them a bit.


Well-Known Member
Here's a picture of the hemispheres with the second coat of Alclad II Gloss Black Base (the pair at the back are earlier prototypes made to fit the thumb switch from Roel Veldhuysen's 3D model). Some dust has settled in the paint, but I'm not worried about that. These are prototypes anyway, and at least one of them will be weathered.


And here's a pic with the switch and red lens:

Next up is the applying the Alclad Chrome, looking forward to doing that.


Master Member
you are getting a really great result out of your 3D printed parts, great job! I also love the look of the slightly cracked chrome you did above!


New Member
Love your build!

I just purchased a very nice kit from Etsy which includes the sound board. The maker 'ScaleMark Models' has put a series of videos out on how to put it together, which may be of interest to you, especially the part on putting in the sounds and painting



Well-Known Member
Love your build!

I just purchased a very nice kit from Etsy which includes the sound board. The maker 'ScaleMark Models' has put a series of videos out on how to put it together, which may be of interest to you, especially the part on putting in the sounds and painting


And thanks for sharing about the sound board, I'll check it out.

I managed to put down a coat of chrome on the first prototype, and I like it!


The dust embedded in the black gloss undercoat reads as wear to me, so that's positive (even though this is just a test).

And I once again experienced that the more opaque the chrome layer the brighter the chrome, but also the duller the finish. So I had to find the sweet spot, making the chrome a little bit darker but still keeping a lot of the shine.

I'm very happy with the colours over all though!

And lastly, check out the reflection of the LED's here :cool:
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