a bit of a D'oh moment on my part...I totally ignored the part of your request relating to thumbs and focused on the free part...sorry...Deep Exploration may have a 'lite' version or a demo but that's the only one i know of that does thumbs of models. There is a Poser explorer/viewer that does .obj in free stuff, dunno it's name but checked it out and with no Poser, no need, but that's 'bout it from me...Any others out there with ideas?

 

Once in a while I look around,
I see a sound
and try to write it down
Sometimes they come out very soft
Tinkling light sound
The Sun comes up again