I recently had a project that required the creation of a number of materials for the same object. Making minor changes and seeing how these looked when rendered got to be very time consuming and tedious. After taking some time to play with the Material Manager I realized that I can add my own objects to the material preview window and see exactly how those materials are going to look on my object. It made the process of creating new materials move much faster and saved me hours of tinkering and rendering. This process is really intended for a project that needs multiple materials for one object but can be used for anything. You can also create a custom object of your own just for the fun of it and use it to test your materials! As noted in the tutorial, I have included a download for the template that I use to create those object previews:
Object Preview Template R11+
These template files will work for Cinema 4D versions Release 11 and up.