12 v G4 leds on a mega 2560

I am attempting to light 48 Leds on a arduino mega using 12v leds I have my sketch that is working with regular 5mm 12v leds but they are not bring enough. How do I get the G4 Leds to light up on the board?

Use a 12V supply and a buffer chip that can take 12V & higher currents.
ULN2803, TPIC6B595, single NPN or N-channel MOSFETs can all sink current from 12V sources.
I don't know what a G4 LED is, so other considerations might also come into play.