Use lower resolution photos and images in your models. Textures and images saved with SketchUp are raster files with varying degrees of pixel density. This variation can affect file size. You can purge unused materials, or you can use a lower resolution material.In the Materials panel you can identify materials referenced in your model by a small white triangle. You can Purge Unused from the commands in the Materials panel.

3D Warehouse provides a few ways for you to find the materials you are looking for. You can always search for a material and download it into your model. You can also download materials used in the models that other users have added to 3D Warehouse. To download a material used in another model without downloading the whole model, follow these steps: