Ayam is a free 3D modelling environment for the RenderMan interface. It features good RIB export, CSG (all RenderMan primitives supported), and NURBS modelling. Features instancing, arbitrary number of modeling views, object clipboard, independent property clipboard, n-level undo, console, and Tree-View with Drag-and-Drop support.
BALLView is an extensible viewer for bio-molecular structures. It provides all standard models and offers rich functionality for molecular modeling and simulation, including molecular mechanics methods (AMBER, CHARMM, and MMFF94 force fields), continuum electrostatics methods employing a Finite-Difference Poisson Boltzmann solver, secondary structure calculation, molecular editing and docking. Since BALLView is based on BALL (the Biochemical ALgorithms Library), it is easily extensible on the level of C++ code. In addition, it provides a Python interface with Integrated Development Environment features to allow interactive rapid prototyping.
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
Brook for GPUs is a compiler and runtime implementation of the Brook stream programming language for modern graphics hardware. The goals for this project are to demonstrate general purpose programing on GPUs, to provide a useful tool for developers who want to run applications on GPUs, and to research the stream language programming model, streaming applications, and system implementations.