Actually AutoCAD sucks for 3D designing - unless you are talking about Mecahnical Desktop or Inventor. I use Unigraphics everyday at my day job (hi-end 3D solid modeling package, very similar to Boeing's CATIA if you know what that is). A very good alternative is SolidWorks and is more affordable for smaller businesses. It's still around $3-$5k for a copy, but that's nothing compared to somewhere in the neighborhood of $25k a seat for Unigraphics (plus the monthly fees and other garbage they hit you with). I know very very little about CNC routing for signs, but have done CNC work on a metal lathe and mill, so I do know how those operate and would assume signage would be similar. I used 2D AutoCAD for some simple metal parts, but would not use it for 3D work unless someone has made a plug-on module for it that I'm not aware of. Would like to get into this, but it seems WAY outta my financial reach right now.