Definition to Automatically arrange (2D) geometry in given area for fabrication (no overlap)

Title says it all.  I have written a definition to slice up some 3d geometry in a specific way and it spits out 2d cs, ready to be cut, nice and neat on a grid.  However it is often the case that if I were to just go ahead and laser cut or CNC, a huge amount of space and thus material would be wasted. I can manually go in and arrange my shapes so that there is as little dead space as possible but once I have hundreds and up to a thousand shapes, this can take a very long time...Any ideas for a definition for this one?

In short:

Given a set of (2d) geometry on the same plane write a definition that fits as many of them as possible in a given area with 0 overlap.

Also -- be able to specify the maximum closeness of each piece, so as to add padding for the width of the CNC drill bit cutting them out.