The Rainbow Lightbox uses an array of mylar tubes to create beautiful pixelated shadows from colored light. I was inspired by Taizo Matsumura’s “Hikari no Hako” kit, which is a small paper box filled with mylar tubes. I created my own larger version with hundreds of mylar tubes and instead of relying on colored filters, as Matsumura’s kit did, I used multicolored light and shadows to create a unique effect that brings out every color of the rainbow.
By experimenting with different light sources, from sunlight to televisions, I discovered that the mylar tubes do something surprising with colors if you sandwich them between two diffusion filters. When one end of a mylar tube is exposed to multiple colors, the tube mixes the colors together to create a new color that is projected onto the top diffusion filter. Although the colors that go into the tube array can vary smoothly, because of the sharp borders created by the edges of the tubes, the image that emerges has a beautiful pixelated appearance.
I also set about creating a colorful input to illuminate the lightbox, using red, blue, and green LEDs. When these colors are combined they create white light, but if you block them they cast colorful shadows onto the back of the lightbox. The colored shadows are re-mixed by the mylar array and emerge on the other side in every possible hue (Figure A).
The result is the Rainbow Lightbox: a device that lets you mix colored light like paint and play with color by casting shadows.
Build the Frame
On one end of each board, mark two screw holes that are ¾” in from each of the long edges, and ⅜” in from the short edge (Figure B). Use a 3/32″ bit to predrill the screw holes. Countersink each hole (Figure C) — this will keep the wood from splitting when you screw the boards together. Line up the holes on one board with the undrilled end of a second board. Use a 3/32″ bit to carefully drill through the first hole into the end of the second board. Screw the boards together with a 11/2″ wood screw (Figure D). Repeat with the second hole. Repeat the whole process until you have a four-sided frame (Figure E).
Add the Acrylic Panels
Mark ⅜” in from the edge of each acrylic sheet, all the way around. Evenly distribute 16 screw holes around the edge of each panel, starting 1″ in from each corner (Figure F). Use a ⅛” plastic bit to drill holes where the screws will go. Set your drill to a high speed and use low pressure to keep the plastic from cracking when you drill through. It also helps if there is something to drill into underneath the acrylic — a piece of plywood should do the trick (Figure G).
Place one of the acrylic sheets on top on the wood frame and secure it with painter’s tape. Use the 3/32″ bit to drill through each hole (Figure H). When you’ve drilled all the holes in one side, flip the frame over and repeat the process with the second acrylic sheet. Mark where each sheet lines up (Figure I — trust me, you’ll never remember!) Remove the acrylic sheets, and set one aside for now.
Remove the protective covering from one side of the other acrylic panel (Figure J). Line the panel up with one of the diffusing filters, and use a bit of scotch tape to hold them together (Figure K). Carefully cut out the holes in the diffusion filter with an X-Acto knife (Figure L). Place the filter/acrylic sandwich back on top of the wood frame, filter side down. Peel the protective covering away from the screw holes and use ¾” wood screws to attach the acrylic panel to the frame (Figure M).
Make the Tubes, Lots and Lots of Tubes!
Invite some friends over for this part with offers of cookies and beer; the work goes a lot quicker with good company! Cut the mylar into long, 3″-wide strips using an X-Acto knife and a ruler (Figure N). Lots and lots of strips. When you have a big pile of 3″ strips, cut them down into 3½”, 4½”, and 6½” lengths (Figure O — the three lengths are for the different dowel diameters).
Now comes the cookies and beer part! Wrap a piece of mylar around a dowel to make a tube. Secure the mylar tube lengthwise with a strip of scotch tape (Figure P). Slide the mylar tube off the dowel and place it in the frame (Figure Q). Keep adding tubes until the frame is packed tight (Figure R). When you’re satisfied, place the second diffusion filter on the filled frame, followed by the acrylic panel (aren’t you glad you marked how it goes together?). Cut out the holes in the filter with an X-Acto, and screw it together (Figure S). Remove the protective coating from both sides of the lightbox (Figure T).
Make a Heatsink
Super bright LEDs can put out a lot of heat (along with a lot of light), and it’s important to give your LED a heatsink to dissipate that heat and keep your LED from burning out.
Use the ⅛” bit to drill a couple of screw holes on one side of the aluminum angle. It helps to put the angle on a block of wood for this part (Figure U). Place the LED on the other side of the angle, and mark the hole in the LED’s center, and where you want the two 4-40 screws the go (Figure V). Drill the center hole with the ⅛” bit. Drill the two holes with the #43 bit (Figure W). Use the 4-40 tap and a little cutting fluid to thread the #43 holes (Figure X). Line the aluminum angle up with the edge of the 4″×4″ wood block and screw it down using two ¾” wood screws (Figure Y). Put the LED in place and screw in the two 4-40 screws. Tighten them down with the 3/32 hex key (Figure Z).
Build Your Light Source
Thread the BuckPuck’s LED (+) and LED (-) wires through the center hole (Figure AA). Solder them to the LED’s corresponding positive and negative pads (Figure BB). Use the slotted screwdriver to screw the BuckPuck’s positive and negative wires into one side of the terminal block (Figure CC).
Plug the pigtail into the power supply jack and screw the positive and negative wires from the pigtail into the other side of the terminal block (Figure DD). Add a p-strap to hold everything in place (Figure EE). Plug in your light (Figure FF)! (If it doesn’t turn on, double-check the polarity of the wires.)
Find a dark space to play with your Rainbow Lightbox. Plug in your light, and shine it at the back of the lightbox (move the light around until you find the sweet spot where the whole lightbox is illuminated). Try casting colorful shadows by blocking the light with your hand. What happens if you move your hand closer or farther from the light? What colors do you see on the back of the box? What colors can you see on the front?
Try using different objects to create colored shadows, like lenses, water, mesh, crocheted lace, perforated metal … look around you for things that might make interesting shadows or patterns (Figure GG). You could also try using different colors for the lights, or other light sources, like a sunny window or a television. If you want to go further, you could activate your lightbox with a mechanical shadow sculpture, turn it into a beautiful lamp, or make several lightboxes and stack them together to create an immersive environment. You can also play with the dimensions of your lightbox. I turned mine into a small table that several people can sit around to play with collaboratively. I think that what makes the Rainbow Lightbox so special is the way it reveals the beauty and physics of light through play and exploration.