One working 3d package for Tcl is 

The Nebula Device is an Open Source 3D game and visualisation engine, see http://www.nebuladevice.org

It is available at SourceForge.  
The binary distribution comes with customized interpreters 
with built-in 3d capabilities, and some demos.  

Try it out... it's impressive.

----
[Category 3D Graphics]