The DXF files included with the plans can be used by fabrication shops to laser cut parts for your build, which can be both cost- and time-effective.
DXF files are a common file for transferring CAD data between different systems. It is a file that can be read by most CAD systems including that used by Laser Cutting Services. Some DXF files are provided and could save you the manufacturing time, and possibly the cost of buying large quantities of material to produce a relatively small part.
Download a free DXF file viewer here