user15132: I'm quite new to these things and I need some help. I'm building a computer shelf with plexiglass and RGB LEDs (one per length) and I need some help to sketch up a data sheet of some sort for this. 
I'm thinking of using an Arduino Uno, but will it be able to run 12+ LEDs?

user3917: If your RGB LEDs are WS2812-style, 5050-size units, it is no problem to control dozens of them using an Arduino Uno or several other models of Arduinos.  [For ATtiny systems, other libraries than Adafruit's NeoPixel may be needed; the NeoPixel library keeps several bytes of state data per pixel, which some other libs don't.]
WS2812-style LEDs typically are arranged in serial strings, driven by a single IO pin from an Arduino.
If you have more than half a dozen WS2812s in the string, power for them should come from an external power supply, rather than via an Arduino's built-in 5V regulator.
For more information, see related questions like Arduino with WS2812 using Adafruit NeoPixel library fade in/out different patterns, and Arduino and WS2812 RGB LED Strip "freezing", and  fading colors on a ws2812 strip; also see Google search Arduino Stackexchange for WS2812.

15132: <p>I'm quite new to these things and I need some help. I'm building a computer shelf with plexiglass and RGB LEDs (one per length) and I need some help to sketch up a data sheet of some sort for this. </p>

<p>I'm thinking of using an Arduino Uno, but will it be able to run 12+ LEDs?</p>
 3917: <p>If your RGB LEDs are <a href="http://www.ebay.com/sch/i.html?_odkw=WS2812+7++5050++Round&amp;_osacat=0&amp;_from=R40&amp;_trksid=p2045573.m570.l1313.TR2.TRC0.A0.H0.XWS2812+++5050++.TRS0&amp;_nkw=WS2812+++5050++&amp;_sacat=0" rel="nofollow noreferrer">WS2812-style, 5050-size</a> units, it is no problem to control dozens of them using an Arduino Uno or several other models of Arduinos.  [For ATtiny systems, other libraries than <a href="http://www.adafruit.com/category/168" rel="nofollow noreferrer">Adafruit's NeoPixel</a> may be needed; the NeoPixel library keeps several bytes of state data per pixel, which some other libs don't.]</p>

<p>WS2812-style LEDs typically are arranged in serial strings, driven by a single IO pin from an Arduino.</p>

<p>If you have more than half a dozen WS2812s in the string, power for them should come from an external power supply, rather than via an Arduino's built-in 5V regulator.</p>

<p>For more information, see related questions like <em><a href="https://arduino.stackexchange.com/q/10357">Arduino with WS2812 using Adafruit NeoPixel library fade in/out different patterns</a></em>, and <em><a href="https://arduino.stackexchange.com/q/17940">Arduino and WS2812 RGB LED Strip "freezing"</a></em>, and  <em><a href="https://arduino.stackexchange.com/q/13136">fading colors on a ws2812 strip</a></em>; also see <a href="https://www.google.com/search?num=50&amp;hl=en&amp;q=site:arduino.stackexchange.com/questions+WS2812+-newest+-recently" rel="nofollow noreferrer">Google search Arduino Stackexchange for WS2812</a>.</p>
