How do I create an outline of entire design with a single vector (for banner cutting printers)

Question

I have a design that we want to have printed in a large banner format.  We have access to one that also has a tool that will cut it out also.  I was told to do this, I need to create a separate swatch color that has a special name to it.  Ok, no problem....  The problem is the design I made is very detailed around the edges, not just a simple square or circle.  I know I would somehow use the options in the pathfinder tool to merge everything into one single object with just a single vector going around everything (also vectors for cutting out the insides of characters such as O's, R's, etc...).  Everything I try seems to merge only some of the objects or I just get errors, or just does something completely unexpected.  What is really the correct way of doing this?

Answer 1

Try this:
1 select all the art
2. Group the art (if not already Grouped)
3. Copy (Command C or Control C)
4. Paste in Front (Command F or Control F) or Paste in Back (Command B or Control B)
5. While to pasted group  is still selected Use the Pathfinder tool to Unite (first icon on the upper left of the Pathfinder Panel.
6. Make sure it has a fill of None and a stroke of your cutline swatch, I think it has to be a stroke weight .125 pts.
Optional
7. If the art is not going to bleed off the cut then select then target the compound path, you just made with the Pathfinder, in the layers panel
8. o the Effects>Path>Offset path and give it an offset amount.
Sort of like this
Here it is with the compound path selected with the offset path, without the offset the cutline would be like the selection
path in the screenshot but would have no fill and only the cut line. You would still need to give it an offset to get the cutline to the edge of the art as the path is aligned to the center of  the strokes, that is if it bleeds and you would have to bleed the art where it overlaps the cut line. That's another story.
You can use the stroke panel to align the path to the outside of the if you do not want to use the Offset Effect and you can also use the Object>Path>Offset Path instead of the effect.
I do not think you should be joining paths if the art is not created that way unless you consult the creator.