Today I got to use a small milling/drilling machine to drill the 5mm sized holes in the front reflector for the LEDs, using such a machine ensures that all the LEDs point in exactly the same direction to give you a spotlight effect.
Using masking tape & a digital micrometer to mark out the spots where I wanted the LEDs I then drilled them, only one LED can be used in the middle of the reflector because of the mounting points (that can be seen on the back images). The masking tape came off in one piece (which was nice). Not all the holes were precicely aligned down to the 1/10 millimeter but that's ok because when the LEDs are installed and switched on you won't be able to notice.
I had to spin the drill at high speed and drill down slowly so the front doesn't crack, my first attempt by just using a hand drill cracked the front in half but being glued to the black back it didn't fall apart.