I just picked up a good book, but I had no way to read it in bed. My only lighting was the ceiling light, which would shine directly into my eyes. Rather than bear the effort of sitting up to read, I decided to hack together a reading light with parts I had on hand.

Step 1: Design Principle

- LED booklights have been around for years. They clip to a book and an LED extends on a flexible stalk to illuminate the pages. But the design has got it all wrong. Why clip an lamp onto a book when you can implant one right into your forehead? Then it doubles as a hands-free night light that goes with you anywhere!

With 60mW of high efficiency cat-like night vision, you could reduce your carbon footprint by using less electricity. You'll need less of your high powered indoor lighting. And by reading more, you'll reduce the electricity consumed by your TV and your computer. By being a bookworm, you'll burn less calories and need less food, which will drive down the global price of food. In time, Zimbabweans may be able to buy more than one egg with Z$50 billion. This could be the solution to all the world's problems. I just hope it catches on in time. ;)

Step 2: What Is It?

Ok. Cybernetic implants are still a few years away for most of us. So I've settled for a light that clips onto a hat. Yeah, you can buy something like this for a few bucks, but I had some specific traits in mind (and luckily had the right parts on hand). This light is specifically designed for reading in bed! To that effect, I made it with a Lambertian, wide-angle LED, which I am running at only 1/10 its maximum rating. I also made it as lightweight as possible.

So what you need are:

a piece of foam board, approx 1 3/8" x 3 3/4"
a soft, white, LED with wide angle Lambertian dispersion pattern
a toggle switch
a small lipoly battery
a 20 ohm resistor
a heat gun
a glue gun
SIP header
wire, solder, soldering iron
a baseball cap

Step 3: Body

PVC foam board:

This will provide the structure upon which the light is built. The right stuff for this job is 3mm thick PVC foam board. The stuff I used goes by the tradename of Sintra.

The main reason I'm using PVC foam board is because it's easy to cut and heat-form. It's also very light.

So here's how you do it. Cut out a 1 3/8" by 3 3/4" rectangle, or thereabouts. Heat it over a heat gun until it gets floppy. Then fold it in half and press it around the brim of your hat.

Here's a video:
http://s18.photobucket.com/albums/b103/klee27x/?action=view&current=FoamBoard.flv

Step 4: Power

Lithium polymer battery:

Well, I happened to have a very small lipoly battery lying around. I lost my bluetooth headset the other week, and I later found it smashed up in the parking lot where I must have dropped it. It was beyond repair, so I salvaged the battery.

If you want a battery like this without waiting for your bluetooth headset to break, sometimes you can find replacement batteries for mini RC helicopters. Here is a pair of similar batteries I just happened to spy on Ebay:

http://cgi.ebay.com/2-Micro-Mosquito-Firefly-RC-Helicopter-Lipoly-Batteries_W0QQitemZ370188528943QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item370188528943&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A15|39%3A1|240%3A1318

Another way to do it would be to buy a cheap bluetooth headset ($10.00 and up) and convert it to a banana-phone (or maybe stick it into the frame of a comfortable corded external headset). And while you're at it, change the battery out for one of the larger batteries from your stockpile. That's how I got my second battery, which I used to make this Instructable.

Step 5: LED

I used this LED. I forget the specs, other than it's a Cree LED on a round, 14mm heatsink. The power isn't really that important. The most important thing is that it has a nice even dispersion over a wide field of view. This has a wide angle Lambertian dispersion pattern, so it's perfect for the job of illuminating a book a couple feet from your face.

So with this LED I soldered the resistor right onto the heat sink, then glued it in place. It's pretty self-explanatory.

Step 6: Switch

So put the switch on, and wire everything up!

Step 7: Done

So here's the result. It weighs only 12.9 grams.

Here's a video demonstrating the grip. It's impressive! This light will never accidentally fall in the toilet, unless it's accompanied by the rest of the hat. :)

http://s18.photobucket.com/albums/b103/klee27x/?action=view&current=CatVision020.flv