This project first appeared in MAKE Volume 38, on pages 86–87.

Minority Report and Iron Man-type interfaces are already here — you can control your computer’s functions from a wall or tabletop or just by waving a wand in midair. It’s amazingly affordable if you use a Wii Remote and an infrared (IR) light pen. How do you get an IR pen? You make it!

In 2007, Johnny Chung Lee invented the Wiimote whiteboard. As Lee explained in his runaway YouTube video, every Wiimote has a high-resolution IR camera. To turn it into a mouse or an interactive whiteboard, we connect it to a computer, fix it in one place, and use movable IR pens within view of its camera.

An IR pen is a simple device — basically a flashlight with a momentary pushbutton and a high-power IR LED like you find in TV remote controls. Most people use a dried-up dry-erase marker as the body of their pen, but performance is spotty because the LED points out the end of the pen, not straight at the Wiimote camera.

So I designed a big IR pen with the LED pointing out the side, and turned it into a small business. It’s the longest IR pen in the world!

Project Steps

Wire the IR LED.

Split and strip both ends of the 2-conductor speaker wire. Trim the LED leads evenly and solder them to one end, taking note of which conductor goes to the positive lead, and which to negative. Insulate all connections with electrical tape or heat-shrink tubing.

Tear down the toy saber.

Remove all screws, then take out the batteries, battery connectors, internal switch, and external button, and separate the handle shells from the “blade.”

Install the IR LED.

Drill a 13/64″ hole in the side of the blade, near the tip. Cut a small flap to open up the hole, then feed the speaker wire down the hole until it emerges from the far end. Mount the IR LED in the hole with hot glue, then push the flap back down.

Replace the internal switch.

Desolder the saber’s original toggle switch and positive battery connector (save the original string of LEDs for another project). Solder your momentary pushbutton to the positive battery connector and the positive wire from the IR LED, wiring it in the “normally off” mode.

Depending on your saber, you might need to support your pushbutton with a little wire bridge or hot glue so that it fits right. I also added a small gob of hot glue to extend the original external button, so it will reach the new pushbutton inside.

Add the resistor.

Solder the 33Ω resistor between the negative battery connector (the one with the spring) and the negative wire from the IR LED.

Reassemble and test.

Solder the 33Ω resistor between the negative battery connector (the one with the spring) and the negative wire from the IR LED.

Press the button. You can’t see infrared light with the naked eye, so look at it through a digital camera, like the one in your cellphone. You should see the LED glow a bluish color in your camera!

Finishing touch.

Neatly cover the slit in the top of the saber with white electrical tape. You can use a paper hole punch to make a hole in the tape to fit the LED.


What can you do with your IR saber? Anything your computer can do, except bigger, better, and more badass. Create a free PC theremin, play chess or solitaire on your wall, or browse family photos and internet videos. Have a fake laser battle with your kids, teach a class, or give a presentation. You can even build two IR sabers and do multipoint whiteboard control.I show how to set up my Smoothboard system in my videos at youtube.com/user/Shakespeare1612, and there are lots of tutorials and software online for similar “Wiimote whiteboard” setups. Enjoy!