Good ideas. However, the main physical difference is that factory patch cables are stranded wire. Many times patch cables made in the field are made from solid wire used for cabling. It does work, but will not have the ability to be moved and twisted without disruption as well as stranded wire will. Also, be aware that the modular plugs installed on the end are different for stranded vs solid wire. There are some plugs that claim they function well with either cable style. Just to make it more complicated as we step into the proposed CAT6 arena, the requirements really tighten up.
For me, I make them in the field if need be. Using quality AMP plugs and a quality AMP ratcheting crimp tool. Sometimes you need one slightly longer than you brought, etc. However, I can purchase 7' CAT5 patch cables for under a dollar. My time is worth too much to sit and untwist UTP in the field unless I need to. Also keep in mind that too much untwisting on the wire prior to insertion can cause the cable to not pass NEXT as well as other tests. If you DO make them in the field, definitely scan them with the same equipment used to verify your data network, or you will be the weakest link!
Daron J. Wilson
Telecom Manager
LH Morris Electric, Inc.
daron.wilson@lhmorris.com