Introduction: How to Light Paint a Sphere

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About: My name is Jack Defay and I am a student and a maker! Check out my work on Youtube @jackandbendefayrobotics | Thingiverse @jackdefay | Github @jackdefay

In my experience with light painting, by far the most important step is to go out and try it. It won't work very well at first, but practicing is the only way to improve your skills and to understand what can be improved in the design. Even before you build a light, go out and make circles with a flashlight or a glow stick tied to a string. You won't know how to design the light until you try it out.

For me, light painting really consists of 3 parts:

1. The actual painting.

2. Building painting tools.

3. Taking the pictures.

This instructables will cover the first two. By the end, you'll be a light artist too!

Step 1: Super Quick Theory

When I first saw light painted spheres I thought they were the most magical thing. It turns out, they are also really simple to make.

1. Spin the light in a circle.

2. At the same time, turn in a circle.

Since light painting is additive, by turning in a perpendicular circle to the one you spin you create the image of a sphere.

When you first start, your spheres will probably look super messy. This is the part that takes the most practice: you have to spin the circle in a constant plane and keep it centered at exactly the same point.

Step 2: Setting Up a Device

When I first saw light painting, I thought it would be a really cool thing to do with an arduino. Arduino is such a versatile system, and works really well for these sorts of simple embedded projects. A traditional arduino like the Uno would be way too big, but fortunately there are a lot of smaller boards to choose from.

I'll walk you through how I made my current setup, but please change, modify or altogether disregard my design. In the end, this is a form of art so it's all about what works for you.

Step 3: The Handle

It might seem weird to start by talking about the handle instead of you know...the light, but it shows just how important I feel the handle is. While I was spinning the light, I realized I could probably improve the design with a 3D printed piece. After a few iterations I was shocked by how much better it was. If you get nothing else from this instructables, try out this handle:

https://www.thingiverse.com/thing:3336836

I would suggest printing the handle with the wide face down with 3-5 walls and at least 20% infill. This is so the part is strong and rigid enough to sustain large swings, and since there are no large open volumes the infill doesn't impact the print time very much.

The only post processing you really gotta do is sand down the internal edge where the string will be to limit the wear on the string.

To use the handle, take the light off of whatever setup you have and insert the string from the small end to the large end of the handle. Reattach the light and you're ready to go! The notch in the bottom allows you to wrap the string around the shaft of the handle, taking advantage of the capstan effect. Anchoring the string allows you to spin constant radius circles! This alone improved the quality of spheres I was drawing so much.

Finally, you can also use this handle to draw spectacular spirals. I've read about people using the zoom on their camera to create the illusion of a spiral over the long exposure, but this is a true spiral. Just start spinning the light in a circle, then as the picture is being taken start pulling on the string (obviously without wrapping it). Due to the Conservation of Angular Momentum the light will start spinning faster and faster, just like an ice skater pulling in their arms during a spin.

Step 4: The Light!

This is the fun part. Once you've painted a few spheres you'll probably be hooked, but where can you go from there? The power to control the light opens up a whole world of possibilities, from using one light with multiple color options to spectrum cycling to any sort of weird patterns you can imagine. And it's not that hard to set up.

  1. Get familiar with a small Arduino Board. There are tons of Arduino boards, and many would be suitable for this kind of project. I really had two criteria: it had to be small and be powered by a single cell LiPo. I ended up going with an Arduino Gemma because it fit these criteria and I happened to have one on hand. Some other boards that would work are the Pro mini 3v, feather, qduino, trinket 3v, Flora, or even just an ATTiny chip.
  2. Get a small lipo battery. If you're using a board that runs off 3.3v logic like I did, powering it will be really easy. You can find really good lipos from Sparkfun or Adafruit, or you can use small RC lipo batteries. It's best if you get a battery that's about the same dimensions as your board.
  3. Set up a light, preferably RGB. You can buy prefabbed strings of RGB LEDs, again I would suggest the ones by Adafruit. I've also had fun soldering them together myself but this takes some time. You can certainly make due with 1 LED for starters, but the more you use the better it shows up in the pictures.

Step 5: Case Design

We have to attach the light to the string in order to spin it. Again I saw an opportunity for a 3D printed part. Just tie the string or run a zip tie through the holes and connect it with a carabiner and you're ready to go! Here's my model on thingiverse:

https://www.thingiverse.com/thing:3336139

Recently I've been experimenting with flexible TPU and it makes for fantastic casings. Just like if you print it out of PLA it's best to use natural clear so the light shines through. My favorite so far is Sainsmart clear TPU: https://www.amazon.com/SainSmart-Flexible-Printing...

Step 6: Next Steps

And that's it! This is such a simple system but it opened up a world of possibilities for me, and I hope it does for you too. Here are a few ideas I'm working on:

  • Steel wool. This stuff is seriously awesome, just check it out online: https://mymodernmet.com/steel-wool-photography/
  • Other shapes with rotational symmetry. All you need is a way to constrain the way the string spins in some way to make more interesting shapes, Using the handle for example I think I can make really clean infinity symbols.
  • Real time color control with a remote. I plan to develop a remote that communicates to the arduino over rf so I can change the color in real time. This will give me more flexibility and even greater control over the light.

Step 7: Credit and Full Materials List

All the light painting photos here were taken using these techniques and devices. The lower quality photos were taken with a fantastic phone app called long exposure camera 2: https://play.google.com/store/apps/details?id=com...., and the ones that look like real photographs were taken by http://www.lindseyforgphotography.com/ or https://www.instagram.com/princess_1901/ :)

Although I picked most of the parts based on what was convenient or personal preference, I know it's super annoying when you see a cool part in an instructables and they won't tell you what it is. So, here is a full list of the materials I used: