Do you mean how to optimally pack the parts on the sheet so you scrap less material? That's what I'm reading at least.
We use some at work. You won't get them without spending a zillion dollars.
What I'd do is cut miniatures out of paper in the shapes you want cut, and arrange them by hand on a piece of graph paper or something. You'll probably get very close to what the computer would, it'll just take you a bit longer.
Or if you're sending the work out, whoever you're contracting should be able to do it.
If you mean a program to calculate toolpaths for a laser cutter or waterjet, you can use
LinuxCNC, but it doesn't sound like that's what you're looking for.
