This looks interesting: Instant Object Maker allows you to build and place your own photoreal object into FS2004 or FSX with absolutely no modelling experience -- all you need is a photo. I must admit it doesn't really suit me (it doesn't make FSX-native code, for instance) but it may be just the thing for someone who wants to build their local airfield without going to a lot of trouble.
...wow progress is fast.
I can remember making not only my house, but also the tree in front, in FS5...and that capability was built into the sim!