CDV has released an add-on for their city-building game City Life. The add-on is a special building design toolkit for use with the game's models, allowing players to modify the existing buildings within the game using Autodesk 3ds, and then share these modifications as custom buildings.

Players without Autodesk 3ds can still use the tool to import community-created buildings into their own game.

The add-on can be downloaded from one of these mirrors:
3D Gamers: http://www.3dgamers.com/news/more/1096485027/
WorthPlaying: http://www.worthplaying.com/article.php?sid=34525
GameSpot: http://www.gamespot.com/pc/strategy/citylife/download.html?sid=6152194
FileFront: http://files.filefront.com/City+Life+Design+Toolkit/;5103285;;/fileinfo.html
GameDaily: http://www.gamedaily.com/download/info/?packageid=0078701335
GamersHell: http://www.gamershell.com/download_14132.shtml
GameZone: http://downloads.gamezone.com/demos/d15948.htm

For more information about CDV's city simulator, head over to the official website.