I've used 2D & 3D Design-CAD, CAD and Autocad. Most of the software outhere nowdays allows the file to be converted to anything from .dxf to .plt.
I've even designed in CorelDraw & Flexi-Sign then converted in to a .plt - Imported it to one of my CAD software packages and converted it to .dxf without any problems...
End of the day it's sometimes easier and less hassle just to go to the right guys than trying to do it yourself. Although having said sometimes it's great getting into something new and learning...