I haven't disassembled an LED bulb to look, but it's really doubtful they use such expensive (copper) and space consuming tech. More likely a simple diode or similar.

The cheapest/simplest way I can imagine to build an LED bulb from scratch, would be to just insert a power diode in series with about 80 LEDs (120V operation), assuming each LED drops 1.5V from input to output. Adjust the quantity if the drop is different.

EDIT: actually, the power diode isn't needed, since each LED is a diode already!

Now that bulb will flicker at 60HZ, so it could be improved with a full-wave rectifier, aka. four diodes instead of one, so that it flickers at 120HZ instead. Add a nice capacitor or two to blur the flicker to imperceptible levels.

Commercial bulbs are undoubtedly fancier than that. I really should sacrifice one to the gods of curiosity some day soon!