This is a definition (WIP, attached) which creates sections for a laser cutter from opened or closed single geometry.  This won't work on every geometry, but it will work for a lot of them.  It uses offsets and booleans so it may be difficult to predict.

I'm also playing with a way to minimize material area for cutting (with galapagos).  If anyone can offer help to improve it, let me know! 

Update:

- Some issues with outside sections were fixed by culling perimeter members.

- Section cuts are oriented relative to one another with a cheap standard deviation technique.

- Galapagos optimizer no longer allows sections to intersect.

- Galapagos optimizer now coordinates y and x movement to minimize cutting area of material.

The galapagos run will be crazy in the beginning (will take a lot of area), but should look right after ten minutes or so.

For more on the galapagos run, see this post: http://www.grasshopper3d.com/profiles/blogs/laser-material-optimizer

Definitions (Updated):

SectionModeler.3dm

SectionModeler_Updated.gh

Definitions (OLD):

SectionModeler.3dm

SectionModeler.gh

Video:

http://www.grasshopper3d.com/video/sectional-modeler-for-laser