There are a large number of tools out there on the Internet for building worlds and designing avatars.
Some software is freely available for download for some trial period.
SGI also maintains an excellent site all about VRML worlds and containing many great examples, including Floops, described earlier in this book. Integrated Data Systems sells a powerful VRML authoring system called V Realm Builder 2.0. Sense8 corporation provides a set of powerful source code libraries called WorldToolKit and a 3D authoring system based on them called World Up. Superscape is another company that has been around more than a decade, providing 3D browsers and tools, including VRT, a 3D authoring system. Radiance Interantional offers a VRML 2.0 authoring system for Windows 95 and NT called Ez3d VRML Author.