You can use the free SimLab Composer Lite! http://www.simlab-soft.com/3d-products/simlab-composer-lite.aspx
It's open quasi all 3D Files formats!
Except alas the 3dm from Moi!!! (but for that you have Moi and the Max Smirnov System! ;)
(for Moi V3 http://moi3d.com/forum/index.php?webtag=MOI&msg=6507.1 )

Here for example the KitBash by Chipp Walters in Moi 3dm files!