Sketchup samples???

The reason is that the existence of a 3D model in sketchup or even one that has been exported into 3dsmax is of limited use in itself. It may be a useful starting point for a CXXL modder to evaluate whether it is a viable project or not. Sketchup models tend to be badly/ inefficiently formed in 3d modelling terms which means there are often inverted or overlapping faces resulting in a 3d model that wastes a lot a triangles. This can be corrected by someone with reasonable skill level in 3dsmax but the effort involved is almost the same as designing the model yourself from scratch where at least you can avoid these problems at the design stage. The 2nd problem is the issue of textures. Most sketchup models use multi materials but the models in CXXL have to run from one single texture bitmap. To get the model into a state where it can be displayed in the game requires that you try to put all these multiple textures onto 1 sheet of limited size and then re-texture the entire model onto your newly created texture bitmap using UV-mapping.

If you are wanting to share models so others can mod them into the game and you have a good 3d model for it, the best way would be to post in the building request thread with as many pictures of the real life building from various elevations as you can find along with a link to your 3ds max or stetchup model. This may attract the interest of one of the modders here who might make it for you or guide you through the process of making it yourself. The community is always in need of active modders and there are plenty of people here who will be prepared to encourage you.