3D Modeling Programs

 3D modeling software is mostly used for making props and characters, but can also be used for generating textures.

• For Source Modelling, the model editor application must be able to export models in Valve's SMD format.

With Half-Life: Source model exporter

• 3DS Max - a high end suite for animation, modeling and rendering. one of the industry's best. Has a large support network and many plugins. Valve used 3DS MAX for the original half-life (hence the name of studiomdl.exe and .smd) there for exporters exists for all versions from 3 to 9, importers for .smd also exists for most versions as well as a .vta exporter and .vtf importer.
• Blender - a high end free, open-source, suite for animation, modeling and rendering. Exporters for Blender currently only support static prop exporting.
• Cinema 4D - a popular modeling program, especially in TV media. It is a powerful toolbox. It's exporter currently only support static prop exporting.
• fragMOTION - a low end modeling and animation suite, but it has tight integration with the structure of half-life models and supports weighted vertexes. FragMOTION comes with .smd importer and importer as well as .vtf importer.
• GMax - a discontinued free version of 3ds Max currently distributed by Turbo Squid. Both, an .smd exporter and importer exist for GMax.
• Maya - a high end suite for animation, modeling and rendering. An advanced .smd and .vta exporter exists as well as a limited .smd importer.
• MilkShape 3D - a low end, popular and simple to use 3D modeling program. Comes with .smd exporter and importer.
• LightWave 3D - an excellent mid range modeling and animation suite. Currently, a LightWave-only exporter supports static props.
• Softimage|XSI - an excellent mid to high end modeling, animation and rendering suite, Valve used XSI for most models in Half-life:Source, the XSI Mod Tool exporter can be used with a little modification.
• XSI Mod Tool - a free version of XSI with limited capabilities compared to the full version of XSI. Valve developed the exporter for XSI Mod Tool together with Softimage (the creators of XSI), and as a result it has full support for importing and exporting .smd and exporting of .vta.

Without Half-Life: Source model exporter

• Wings 3D - a free, open source Nendo-like natural modeling  IDE.