Introduction: The Glowing Eyes Terminator T-800 Exoskull From Thingiverse

About: I'm a Mechanical Engineer turned IT Professional and Author. I came into the Information Technology world because someone challenged me to. But at heart, I'm still a grease monkey with no desire to lose touch …

This project started when I revisited my profile on and ran into the T-800 Exoskull design by DEL_1979 that I had saved into one of my collections, I don't know for how long.

I had an unused roll of eSun Silver PLA+ PRO filament that I thought would fit this project very nicely and decided to 3D print the parts.

And they came out awesome!

But putting such a wonderful creation by DEL_1979 as is without any electronics did not seem to make justice to the time I spent printing this thing.

In this IBLE and the companion YouTube video series, I'll walk you through one of my renditions of the Glowing Eyes Terminator T-800 Exoskull.

Let's get those eyes glowing!

Many thanks and a huge shout out to DEL_1979 for creating such an awesome model! Please check out the DEL_1979s work at!

Step 1: The Parts List

Besides the 3D printer and filament of your choices, we'll need the following:

  1. Parts of the T-800 skull from the original works of DEL_1979 from
  2. Two, 5 mm Red LEDs (any other color may not really go well with the spirit of the classic Terminator)
  3. Two 470-Ohm resistors (Color code: Yellow-Violet-Brown-Gold)
  4. A standard HC-SR501 PIR Sensor module with the dimensions shown on this product page
  5. An optional Mini breadboard for installing the electronics into the model & a standard breadboard of your choice for prototyping the electronics as seen here
  6. A couple of ESP8266-based WeMos D1 mini boards , one for prototyping and another to permanently solder the connections to - it can be WiFi enabled and most PINs are capable of PWM
  7. Solder Iron, helping hands, jumper wires, DuPont connectors, Micro-USB power cable and a powered USB hub
  8. Optional:M3x5L threaded Brass Inserts for the Extended Base assembly
  9. M3 Machine screws
  10. The 3D parts for the Extended Base created and added to this build by me (attached to the last page of this IBLE)
  11. The base Arduino Sketch developed in an Arduino IDE that's tooled up to work with the ESP8266 boards (also attached to the end of this IBLE)

Step 2: The 3D Prints & Extended Design

The original parts from were printed on my CR-10. As these prints were complex I didn't want to risk failure and therefore I printed them out at a slow speed of 50 mm/s and with full Raft and supports enabled.

Total print time was about 64 hours and it was well worth the wait as you can see the results in the companion Part 1 of the YouTube video series.


  • A lot of post-printing clean up is in order
  • You won't believe the amount of support material that'll come out of that little skull!

Extending the Design - A Clarification & Emphasis

As seen in the video, I had to extend the design - I say extend because I did not pull the original work into a design software and modify it.

Instead, I built additional parts to suit the spirit and theme of the Terminator T-800 to put around the original 3D printed parts.

Lastly, I want to emphasize that no software modification has been done to the original works of DEL_1979 for the purposes of this project!

Step 3: Making Ways for the LEDs for the Eyes

The eyes are printed partly filled and will need to be drilled through to make ways for the LEDs.

I haven't tried 3 mm LEDs yet, but they could fit without enlarging the holes.

However, I've used 5 mm LEDs and therefore had to use a larger drill for a second round of drill-through.

For the other post-printing modifications, please watch Part 2 and Part 3 of my YouTube series


Plastic will melt and clog your drill flutes!

Therefore, drill the hole in steps by starting with a smaller bit to remove small amount of material, followed by a larger drill to complete the process.

Step 4: The Circuit Design & Circuit Math

The image is shown in the attached diagram as created in Fritzing.

  • GPIO PINS marked D6 & D7 are used as Analog outputs to work the LEDs
  • GPIO PIN marked D5 is used as a Digital input to operate the HC-SR501 PIR Sensor for motion detection

Sketch for the Glowing Eyes Effect

I didn't want the eyes to simply turn ON and OFF which makes the project less interesting.

Instead I wanted them to gradually brighten and dim 3 times as soon as motion is detected.

Unfortunately, I couldn't use interrupts in the motion detection sketch because the motion sensing is digital, whilst the glowing eyes effect is analog and needs a delay function for the gradual blinking effect.

That said, I've written the LED fade() function without using the delay() function based on the Arduino No Delay Blink article here.

To put it simply, I had to adjust the time when the Motion sensor detects motion, to the time it triggers off to match with the time that it takes for the LEDs to gradually fade in and out

Also, there's a Trim pot on the HC-SR501 PIR Sensor that helps you set this timing as indicated on the PIR product page.

I've elaborated below on how this math came up, but you can use my sketch as is to skip the Math below by simply adjusting the PIR trigger to 3 seconds.

Simple Circuit Math

First, I built the fade() function and adjusted the timing of the LEDs blinking until I felt it was right for my situation and then computed the time as follows:

A. Total Analog range of the LED brightness (0 - 254) : 255

B. Steps through which brightness increases or decreases: 5

C. Wait time between each brightness change: 30 ms

D. Total number of steps for LED to go from Zero brightness to Max brightness (A/B) : (255/5) = 51

E. Similarly, total number of steps for LED to go from Max brightness to Zero brightness: (255/5) = 51

F. Total LED Glowing Eyes cycle : D+E = 51+51 = 102 steps

G. Total Time taken for 1 LED Glowing Eyes cycle = (F*C) = 102 * 30 = 3060 ms (or 3.060 seconds)

Next, I built a motion sensing sketch to simply trigger when motion is detected, and then turn off after the default factory time set in the HC-SR501 PIR Sensor.

I gradually turned the trim pot until the sensor turned off after approximately 3 seconds.

The circuit prototype has been demonstrated in Part 2 of my YouTube video series.

The complete sketch is attached and you can fine tune it to suit your situation.


  1. You will need to tune the Time on the PIR sensor to match the working of this sketch
  2. Conversely,you can alter the variables in this sketch (Steps B and C above) to make the sketch work with your timing adjustment on the PIR sensor.
  3. Unless you can detect the difference between 3 seconds and 3.060 seconds, the timing adjustments are approximate and must be adjusted by feel, touch and visual perception

Step 5: Shrinking the Circuit Down

I had to shrink the bread board circuit down so that it could fit inside of the new base I designed in Fusion 360.

Given the events in the world today, I wanted to be mindful to not order non-essential things online.

Therefore, I decided to solder some DuPont cables directly to a plain WeMos D1 Mini PCB as shown in the image.

Alternately, you can prototype something without soldering on the small bread board as shown in the second image. But it would be difficult to plug in the micro-USB cable to the WeMos even if you filt it inside of the Extended Base.

I prepared the LED harness separately so that it could be plugged in easily later during the assembly.

The PIR sensor hook up is super simple and does not require much explanation!

In the future, I plan to replace this arrangement with a permanent PCB when things get back to normal.

Check out Part 2 and Part 3 of my YouTube video series for more information on the wiring and hookup in the final assembly.

Step 6: The Base for the Electronics

  1. All the electronics were housed in the base that I designed in Fusion 360
  2. To fit the theme of the T-800, I drew the idea from the Gray-White or Gray-Silver buildings of Cyberdyne Research facilities seen in Terminator Part I & Part II movies
  3. My design was based on this one particular image seen here
  4. The additional holes on the sides and front of the top-cover are for future enhancement of the T-800 display

The manual part of the assembly was to locate and transfer the positions of the 3 small holes on the underside of the existing T-800 pedestal onto the top cover of the base I designed.

The pedestal will be screwed on to the base after drilling these 3 holes.

You can watch the assembly process in Part 3 of my YouTube video series.

Files for the 3D Printed Base

  • I've attached the 3D printed parts of my work here
  • Parts for the T-800 Exo-skull can be downloaded from DEL_1979s work on

Thanks for reading my IBLE and watching/subscribing to my YouTube channel!


Step 7: Epilogue

I had more grandiose plans for this model.

Unfortunately, the world is reeling from a very challenging health crisis at this time. And I ran out of filament and other supplies to fully bring my idea to fruition. Consequently, this project would've languished , collected dust in my shop, and never gotten made had I waited for things to return to normal.

In the spirit of playing our part of doing what little we can, I decided not to order any non-essential items for the next few months in an effort to not task the already strained heroes who keep these essential services running despite massive risks to their health, their well being and possibly their very life!

We need to salute them all for keeping the wheels of civilization rolling through this terrible storm!

This project will be improved upon once I've figured out how to work with what I've got in my supply bins.

And I will revisit this project in the near future with more enhancements.

Thanks! Stay Safe, Stay Healthy!