I think you need a bit more help than just the machining of the enclosures.I tried 2 different viewers and couldn't find enough information in the file to understand what it is meant to be.It seems to be just a single piece about 254X150 ish with a few pairs of parallel lines.Could you review the complete drawing and maybe post it as a dxf (ideally R12 format) as not everybody has the version of Autocad you may have used and one of the ways to hook users is to change the file format every version change to "encourage" users to buy the upgrade.The old dxf can be read by almost every CAD system.