I have a technical question about lighting. I'm using some 3mm LEDs to light a structure. Right now, I'm mostly concerned with getting this building lit, but eventually it will need to work on the layout. I should mention that this is the first structure I'm lighting. I using the AC output of my power supply to run the LEDs. My question is, how to I set up the resistors? Do I: 1.) Use 1 resistor to handle all of the LEDs in the structure 2.) Give each LED its own resistor 3.) Something else?