Have you tried doing a SAVE AS and then choosing Part instead of Assembly for File Type? There are options when you do this, so you may have to try a few times to get what works for you.
Most rapid prototypers can pretty much accept any file type these days. Some (if not most) are even ok with native SW files.
However, per Alan, you can save an assy as a part.
Hi Andy, Just call the manufacturer and ask what type files would they prefer. As stated you have options to do save as, if its prototyping they may want a .stl file of each part.
Depending on your end needs if you want to have the files printed as assembly or part, you can send the file as assembly or convert it to part as per method suggested above. The 3d printer will accept any of the format (but do check if that can import a SolidWorks file directly, else send a STEP or Parasolid or IGES)
Fantastic, thanks for all the advice ill give it a go of saving the assem as a part and talk to the 3d printers.
Thank you all,