Hi, You may find that most of the applications out there which are freeware will only support the common databases out there which are also available for free or for limited cost. Teradata will likely not be available in freeware data modelling software. The software I have used in the past which I know supports Teradata are: ERWIN IBM Data Architect You may want to have a look at the following website which gives a number of data modelling software options (mixed amongst UML and other modelling tools). There may be a software package listed that can give you what you want. http://www.databaseanswers.org/modelling_tools.htm Cheers.
The best modeling tools for Teradata that I've seen are the Embarcadero tool and ErWin. Depending upon what you're trying to do, I'd take a good strong look at Wherescape Red as well. Though not a typical data modeling tool, its an excellent data warehouse building tool.