On another topic, I recently purchased a 5 metre strip of RGB LEDs.
These are quite different from the addressable LED strips used in my clocks. These strips consist of multiple tri-colour LEDs (in this case, 60 per metre) wired so that all like-colour LEDs are connected together – often 3 LEDs of the same colour, connected in series. The flexible substrate has four connections: +12V, Red, Green and Blue, that can be cut every three LEDs. Pulling these colour connections (RGB) to ground illuminates all of the LEDs of that colour in the strip. Driving each LED colour with a Pulse Width Modulated (PWM) signal allows you to precisely control the intensity of each colour, so that the entire strip can display myriad colour combinations. Using an Arduino, for instance, due to the current required to illuminate the LEDs (300 per colour for a 5 metre strip @10mA/LED = 3A!) you will need to drive each colour signal from a PWM output pin connected to a power NPN Darlington or an N-type power FET. Driving the LEDs hard will also mean you need a hefty 12V poser supply and heatsinks for the power devices.