Introduction: Back to the Future Mind Reading Hat

About: I have a master's degree in physics and my hobbies are: 3D printing, CAD design, arduino, astronomy, astrophotography, cosmology and sci-fi :)

I have a scientific background and since I remember I was into sci-fi too. Few years ago, I have discovered another passion which is 3D printing. With time I have learnt to design and build my own printers and then I started to learn CAD design. Couple years ago I found out about Fusion 360 and I fall in love instantly. I'm still a beginner and I have a lot to learn, but Fusion 360 allowed me to recreate props from my favorite movies.

In this instructables I will show you how I designed and 3D printed mind reading helmet from classic sci-fi trilogy 'Back to the Future'



- 2m x 10mm OD perspex tube (3D printed alternative available)

- Arduino Nano

- 13 x 5mm White LED's

- 13 x 220 Ohm 0.5W resistors

- 9V battery

- 9V battery clip

- On/off slide switch

- Red wire (1mm to 3mm thick)

- Grey wire (5mm to 8mm thick)

- Equipment wire

- Cable ties

- Super glue (I recommend gorilla glue)

- Solder


- 3d Printer

- Soldering iron

- Screwdriver


- Arduino IDE

- Cura (or any other slicing software)

Step 1: Design Part 1

I have started the design from the coils and cylinders which are quite straight forward to design, but I come across few issues. The original helmet have transparent pieces and at the moment you can't print them on FDM printers. I have decided to incorporate clear perspex tubes (10mm OD and 90mm long).

If you do not wish to mess with perspex, you can use an alternative and 3D print this part, preferably in clear PLA.

As you can see I have designed the coils (red and grey), but I also decided to wind real wire instead. You can 3D print them as an alternative too, but then you will have to paint the coils - the choice is yours.

On the pictures above you can see in what order all the parts should be assembled.

Step 2: Design Part 2

The next step was to design connectors with specific shape to join the cylindrical parts made in previous step. I have created a headband and then I have arranged all cylinders similarly to the original helmet from the movie. After that I had to design few different connectors (length and shape) to connect all the parts together.

When I finished the helmet started to look like the one from the movie, but I'm always trying to add something as I'm not a fan of perfect copies. I decided to add the LED's inside the cylinders and control them with Arduino nano. Adding all the wires, LED's and resistors made it look more 'realistic' plus you can program different patterns for LED's. I even recommend to use RGB LED's which will give you more freedom over the colours you wish to display in the helmet.

Step 3: Assembly Part 1

Below you will find all STL files and, in the name of each file, I have included the number of the parts you need to print, and also the colour of the connector which corresponds to the map above.

After printing, I recommend to assemble all the coils with perspex rod (or 3D printed alternative) and then begin to connect them starting from blue connector. Use superglue and make the initial ring (blue) and leave for 5-8 hours for glue to cure properly.

Then glue the orange and purple connectors, making a dome like structure and then leave it for another 5-8 hours. Finally glue the red and green connectors.

UPDATE: Someone requested to cut headband files in half and I just uploaded the new files. Headband_v2_splited.stl is split in half and Headband_v3_splited.stl is split into 4 pieces.

Step 4: Assembly Part 2

Here you have a diagram for wiring the LED's. You will also find STL files to print box for the electronics (arduino and battery) which you can attach to your belt for example.

If you wish to learn more about uploading Arduino code and setting up STL files for printing, please visit one of my other Instructables:

The code is quite simple. The LED will light up randomly for random amount of time. You can, of course, temper with the code and change it to your needs, especially if you decide to use RGB LED's.

Step 5: Assembly Part 3

Here are the pictures of assembled helmet. As you can see, I have decided to use 10mm clear perspex tubes, and I have also used red and grey wire to wind the coils instead of printing and painting them.

All the cables from LED's I have wrapped around the connectors and then secured with clear cable ties.

I have left about 1.5m long cable from each LED. All of them go into 3D printed box which I can clip to my belt.

I'm not going to lie to you, it's not easy project, but for a massive geek and movie fan like me, it was totally worth to do it. On the 3D model all parts fit perfectly but, as many of you know, FDM printer are not super accurate and, if your printer isn't perfectly calibrated, some parts might not fit. For those who are new in 3D printing, you can use hair dryer to warm up the plastic part and then reshape it slightly to make a perfect fit.

Step 6: Comic Con Time

When I finally finished my helmet, I went to Comic Con dressed up as Doc Brown. Unfortunately, I quote:

'This damn thing doesn't work at all'

I hope you will enjoy this project :)

3D Printed Contest

Runner Up in the
3D Printed Contest