Hi, ahr8tch, getting custom props and whatsits *out* of FP can be a real pain. As yet, only FP can read its own 'drag&drop' BMO format...
I'm not doing much CAD at the moment, but I was heavily into FP, TC and the non-IMSI Poser(TM). That can handle very detailed models of objects and people, but lacks 'construction' tools. It seemed a match made in heaven: Plan and 'massing models' in FP, tweak props in TC, Poser for close-ups...
Poser has a private PP2 mesh format, prefers OBJ-format imports. Given the thriving Poser community, there's a zillion PP2 and OBJ freebies on eg Renderosity. When I found anything that suited my project, I'd convert it to multiple formats with eg Zoltan's 3DOC utility...
Couple of years ago, both my library drive and its 'mirror-twin' on adjacent PC died around the same time. The drives were the same brand, the same batch, there was a manufacturing problem. D'uh. Anyway, my carefully organized libraries of 3DS, OBJ and PoserPP2 mesh objects were *trashed*.
I managed to salvage assorted objects from each, found more in the two PCs' up-load/down-load directories, even found some on the portable drive I attach to my wife's lap-top. I'd originally found most of them on the wwweb, but many links had changed, sites re-worked etc and their free models were long gone...
So, a lot of stuff only existed 'on plan'.
I went through a frenzy of creating FP mini-plans, putting one object on each, saving as DXF. Then I opened them in TC or other modeller, stripped 'space dust' and other rubbish, saved as 3DS...
Like I said, IIRC, only FP can read its own 'drag&drop' BMO object format. Would be nice if IMSI provided a TFP import filter-- I'll put that in 'wish list' !!
Meanwhile, here's the eponymous Block.3Ds...