I bought a 5m long strip of white LEDs (from here, ~$13) that I wanted to integrate inside of the icosahedron I made for the Make Something Big week. The goal is to have the icosahedron in front of my house and welcome me home. The icosahedron has to detect someone walking up to the front door and respond by gently pulsating its internal LEDs.
In order to be able to control the 12V LED Strip using the 3.3V or 5V level logic of the microcontroller, we need a N-type transistor. I used a N-type MOSFET that I found lying around. A useful resource that helped me understand the topology of the circuitry was this tutorial