Stella4D
I just found this. generates 3d polyhedra as well as 4d polychora.
can view 3d nets, cross-sections of 4d polytopes with colored sides.
can create convex hulls or convex cores of 4d polytopes.
creates all 1849 "uniform" polychora.
long list of features. read the web page.
http://web.aanet.com.au/robertw/Stella.html#stella4D
costs money for the non-demo version.