Making actual 3D tokens is hard and is the #1 reason why everyones VTT is in 2D. We could all do a 3D one like the games - in fact by using a game engine it would probably not be all that hard. But the content creation would be... challenging.

To make automatic tokens for 2D images should be relatively easy tho. If I knew the sketchup format then it might be no problem. You can generate the wavefront .OBJ format pretty easily as its all text based. Most apps like blender will import them no problem. Maybe you can get blender to make the tokens...

Getting preexisting common monsters in 3D is not so bad. Here is a forum I use a little tho there are many. Most contain lots of crappy models tho and a few good ones. Theres a lot of rough to get through before you spot your diamond.

http://artist-3d.com/free_3d_models/...hp&count=count