We have some Honey I Shrunk the LED Strips in the store. At an astonishing 4mm width these are wee yet surprisingly flexible and can fit just about anywhere. The wires are even nicely color-coded: black for ground, green for data signal, and red for 3-5VDC power.
Warning! These ultra skinny strips are not protected and are quite delicate. They should not be flexed repeatedly, and need to be handled with a lot of care. Not good for younger folks or beginners - check out our protected NeoPixel strips instead!
There are some things to watch for:
There are 75 LEDs in this half-meter strip (so, the density is 150 RGB LEDs per meter), and you can control each LED individually! Yes, that's right, this is the digitally-addressable type of LED strip. You can set the color of each LED's red, green and blue component with 8-bit PWM precision (so 24-bit color per pixel). The LEDs are controlled by shift-registers that are chained up down the strip so you can shorten or lengthen the strip. Only 1 digital output pin are required to send data down. The PWM is built into each LED-chip so once you set the color you can stop talking to the strip and it will continue to PWM all the LEDs for you
The strip is made of flexible PCB material, with some tape on the back. It does not come with weatherproof sheathing. You can cut this stuff pretty easily with wire cutters, there are cut-lines every 7mm / 0.27" (1 LED each). The data/ground pads are on the top, the power pad on the bottom. You can carefully solder to the copper pads and you're good to go. Of course, you can also connect strips together to make them longer, just watch how much current you need! We have a 5V/4A supply that should be able to drive 1 meter and a 5V/10A supply that can drive up to 10 meters (depending on use) You must use a 5V DC power supply to power these strips, do not use higher than 6V or you can destroy the entire strip
These come in half meter strips with some short wires connected to the input pins. If you buy multiples, you will get multiple half meter strips, they will not come on a continuous strip!
Adafruit's detailed NeoPixel Uberguide has everything you need to use NeoPixels in any shape and size. Including ready-to-go library & example code for the Arduino UNO/Duemilanove/Diecimila, Flora/Micro/Leonardo, Trinket/Gemma, Arduino Due & Arduino Mega/ADK (all versions)