Just learnt about very bright strip LEDs in multiple colours you can get from eBay for about 1 USD/metre. They are grouped in 3s, with a current limiting resistor in each group. The bus voltage is 12V. Specs say they draw 4.8W/m which means 400mA. Since there are 20 groups/m this means the LEDs are run at 20mA. Brightness control would be by PWM.

Certainly this is the sort of thing the power transistors on the board can drive. What sort of lighting to make though? Christmas fairy lights? Home disco? (Very retro 😃.)