Double Helix LED Sculpture

Why I built this

The double helix structure of DNA always impressed me. It is crazy to think that something this complex can form over and over again inside our bodies and work so perfectly. I wanted to create something that shows this shape in a different way and turns it into something you can actually see and appreciate.

After building a clock using side glow fiber from another Instructables project, I really liked the way this material can create light effects. I always wanted to use similar fiber in a project of my own because of the special way it handles light. Instead of just having bright LEDs visible, the fiber spreads the light along its whole length and creates a much softer glow. It almost looks like the fiber itself is producing the colored light, while the LEDs are hidden away. This gives a much cleaner look and avoids the harsh, blinding effect that normal LEDs can have when looking directly at them.

Technical details

The full structure, except for the fiber, is 3D printed. I designed the helix directly connected to the base instead of making it as separate parts to make printing easier and also gives the final piece a cleaner look.

The finished piece is around 22 cm tall and has a diameter of about 12 cm. The DNA helix contains 22 pieces of side glow fiber, each with a length of around 83 mm. This results in a total of 1.82 meters of glowing fiber in the finished piece.

The whole design was made in Fusion 360 and then 3D printed. For the lighting, I used an LED strip with 60 LEDs per meter, which provides enough light to make the fiber glow evenly. The LEDs are controlled by an ESP8266 with WLED as software which allows the colors and effects to be changed easily.

Even with the LEDs running at maximum brightness, the entire lamp only uses 2.6 watts, making it a very low power desk decoration.

You don't need much for this. Tool-wise, a soldering iron and flush cutters/knife is enough. A 3D printer is recommended, but if you don't have one, there are plenty of printing services available, so don't worry.

The material list is also pretty short:

1. LED Strip - 5V 60 LEDs/m, 10 mm wide (for example WS2812B or SK6812) - 1m is enough - amazon
2. Power Supply - 5V USB - amazon
3. Side-Glow Fiber - 3mm diameter, at least 2m - amazon
4. ESP board — an ESP8266 is plenty, but an ESP32 works just as well - amazon
5. Power Connector — I like USB-C breakout boards, but other work as well. Make sure it has 5V - amazon
6. Wire - amazon
7. Heat Shrink Tubing - amazon

Note that the linked items are just what I use. These are often multipacks and way more than what is needed for this project.

First, we need to print the parts. Most of the model is a single piece, the DoulbeHelix. To make printing easier, the individual helixes are connected to the base, and the TopCap simply slides over everything to cleanly hide the internal parts.

The STL named LightPlug is optional. It's just a small plug to fill the holes used to insert the LED strips. There won't be any light bleed since the openings are on the bottom, but if you plan to place the helix on a glass surface, you'll probably want to use them.

The Helix itself should be printed with speeds on the slower side and with low layer height, around 0.12 mm works fine. It should also be printed with tree supports and Supports on Build Plate Only disabled.

I'd highly recommend to print test pieces. My printer is not the best and therefore took some trial and error until I was able to achieve a result of satisfying quality.

While the parts are printing, we can program the ESP. We'll use WLED since it's easy to install and comes with lots of great-looking effects, rainbows included.

1. Connect the ESP to your PC and install the required driver if you've never used that board before. Which driver you need depends on the USB chip on your ESP. All of mine use the CH340/CH341 chip, which requires the WCH CH340/CH341 driver. (manufacturer website download link)

1. Go to the WLED installer website, click Install, and follow the short setup instructions.

1. Once WLED is installed, we need to change a few settings:
2. Go to Config → LED Hardware
3. Disable the Brightness Limiter
4. Select your LED strip type (most likely WS2812B or SK6812)
5. Set Length to the number of LEDs on your strip. Mine uses 23.
6. Set Data GPIO to 2
7. Go back to the home screen.
8. Select Rainbow for both the color and the effect.
9. Finally, create a new preset using the button on the far right. This lets the lamp power on with your saved settings every time.

For the actual build, we need to insert the LED strips through the bottom plate and into the helix. Sometimes the LED strip can get stuck on the inside. If that happens, use a pair of tweezers to carefully push it further inside until it reaches the end.

Once you're done, make sure you can see the entire LED through the first and last hole of the helix.

Make sure you cut the LED strip at the very beginning, as close to the LED as possible. There is a bit of extra space at the end of the helix to account for the PCB, but cutting it close to the LED gives us some additional wiggle room and makes the installation process much easier.

Most, if not all, LED strips have a small arrow pointing in one direction. This indicates the direction of the internal wiring, and it's very important that the arrow points inwards. Basically, you want to push the strip into the helix with the arrow going in first.

If you install it the other way around, it won't light up in the end, and you might spend a lot of time troubleshooting why. Not that this has ever happened to me...

Now we are ready to solder the ESP, power connector, and LED strips together.

The power connector needs to provide a 5V output. It should have two solder pads labeled VCC / 5V / Vout and GND.

Use a (preferably red) wire to connect the 5V side to the ESP's 5V / Vin pin and to the LED strip's +5V pad. Repeat the same process for ground, using a black wire.

Lastly, connect one of the ESP's logic pins to the Din (data in) pad of each LED strip. In step 2 we chose GPIO 2 as our data pin. If your pins are not labeled you can google for your exact board name followed by "pinout". This will tell you which pin is GPIO 2.

I'd highly recommend adding a bit of solder to the LED strip pads first. This is called pre-tinning and makes attaching the wires much easier and prevents you from having to heat the pads for too long.

At this point we can power everything up using the power connector, not the ESP's USB-port, and give it a test.

After making sure the electronics work, we can install the top plate. Keep the USB cable plugged in and place the plate on top of the helix. Now screw it down, similar to closing a jar.

Once you reach the bottom, make sure the cable goes through the hole and that the top plate sits flush.

We will need 22 pieces of side-glow fiber, each roughly 83 mm long. Measure the first piece and check the fit. If necessary, shorten it or cut a new, longer one. Once you've found a piece that fits well, use it as a guide for cutting the rest.

Cutting is best done with flush cutters or a sharp knife.

Keep in mind that this is a handmade project, and there is no need to make every single detail perfect. Small imperfections are part of making something yourself and usually do not take away from the final result.

My own version also has a few small imperfections. The print quality is not completely flawless, there are a few spots where solder ended up on the 3D print, and I slightly burned the print while soldering. These things can happen during the building process, especially when working with a combination of 3D printed parts and electronics.

The important thing is that these small details are barely noticeable in the finished project. Once the lights are turned on, the glowing fiber is what catches the attention, and the helix still looks amazing despite these little imperfections. A handmade project does not have to look factory made to be great.