A constant current power supply can be used to drive multiple parallel strings of LEDs. Imagine that each string consists of twelve LEDs, each requiring 350mA and having a drop of 3.5V. Twelve LEDs in series have a typical voltage drop of 42V, which is twelve times 3.5V. Each of the four strings is balanced with a resistor such that each draws an equal current of 350mA. In total, the four strings draw 1.4A, or four times 350mA. The total power that the supply needs to provide is 58.8W. For safety margin, the supply should be specified at 75 or 100W, constant current 1.4A, and have an output voltage range of say 36 to 48V (or more).