I want a tri-bored mag, but don't know why

I am currently building a custom 3D maglite with mods top to bottom and hopefully some machining from our own ajesus Hernandez, and I have bought yet another host mag. It's another 3D and I would like to build it into a useable custom light with top spec performance. As I currently understand it, tri boring is to accomodate more cells in the body of the light for driving different emitters. What I would like to know is what sort of tri boring and cutting down (1D, 2D etc) would be suitable for driving one of the D size p7 malkoff devices maglite dropins?

All I need is an explanation of the purpose of tri boring and some ideas for what to do with my latest mag host!

TIA,

Matt

BumP - BTW mods please move this to the custom lights forum if you feel it is in the wrong place. I wrote it in a hurry on my iPhone at lunchtime today and never thought about where it should go!