BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.
LDraw™ editor for LEGO® style digital building instructions.
LPub3D is an Open Source WYSIWYG editing application for creating
LEGO® style digital building instructions. LPub3D is developed and
maintained by Trevor SANDY. It uses the LDraw™ parts library, the
most comprehensive library of digital Open Source LEGO® bricks
available (www.ldraw.org/ ) and reads the LDraw LDR and MPD model
file formats. LPub3D is available for free under the GNU Public License v3
and runs on Windows, Linux and macOS Operating Systems.
LPub3D is also...
Tool kit to use with RenderMan(R) compatible renderers. Include Blender->RIB exporter, shader editor, procedural geometry generators and other useful tools.