Posted for "Dave Saylor" <Dave@AirCraftersLLC.com>:

 I know what you mean.  There are certain things you're not expected to
 fabricate, like engines and instruments.  There is a list of those things in
 AC 20-139, but it is not an all-inclusive list but rather a set of examples.
 I believe the idea is that if an approved manufacturer would normally buy it
 in order to construct an airplane, then so could you.  But if you do
 construct your own prop or brake discs or bolts, then yes, you should take
 credit for doing so.  It doesn't have to be on the FAA's list to get credit.
 You can add to the list yourself.
 
 Dave Saylor
 AirCrafters LLC
 140 Aviation Way
 Watsonville, CA
 831-722-9141
 831-750-0284 CL
 www.AirCraftersLLC.com
 
[ Dave, as you were involved with the FAA focus group I'd be
interested on your take of the FAA's proposed guidelines. -Rob ]