Truespace (version 3.2)
Truespace is a modeling program developed by the Caligari company. In 2008, Microsoft took over the program, but they did not develop the program anymore. The last version 7.6 became freeware. Since augustus 2012 , the website of Caligari went offline. However, Truespace is still used a lot in Activeworlds, as the file extension of Truespace (.cob) can be used directly in Activeworlds.
There are several versions of the program, TS3.2 was a popular version.
The final version 7.6 was freeware, and has more features , but is more complicated.
Since the Caligari website went down, you'll need to search on the web to find a dowload of the version of the program. Version 3.2 is older and might not be compatible anymore with the current operating system of your computer, then you might try version 7.6.

Click upon the buttons below :
Truespace 3.2 - Overview of the Truespace menu
Truespace 3.2 - Making a simple bench in stone.
Truespace 3.2 - Modeling techniques