5ced8212_World_Building_Tools__Tools_used_to_create_a_world
[Virtual world environment] ID's Quake [Tools used to design avatars] Avatars can be built within the Quake authoring system. [Tools used to create a world] 
A Quake Level Builder is distributed as shareware. Other companies, such as Virtus, also offer Quake builders.
World Building Tools
Tools used to create a world