Blender

Blender is the free and open-source 3D creation suite. It supports the entirety of the 3D pipeline—modeling, rigging, animation, simulation, rendering, compositing and motion tracking, and even video editing and game creation. Through user plugins, it supports older game model formats such as Quake & Hexen2's *.MDL, Quake 2's *.MD2, Quake 3's *.MD3, and Quake 4's *.MD5. Blender's website

Add-ons

Here are some addon adding support for the following formats.

.mdl : classic vertex animated format.

• Khreathor's mdl Blender addon based on Bill Currie's outdated quake forge version for Quake / hexen2

.md2 : The mdl format used in quake2. Works up to current b3d version 3.3.1

• Parli's mdl-md2-md3 addon for Blender based on Khreathor's

.md3 : A more precise mdl used in quake3. No longer works in newer b3d versions.

• Parli's mdl-md2-md3 addon for Blender based on Khreathor's

.md5 : Used in doom3 & Quake Rerelease.

• MD5 Importer/Exporter for Blender 2.80 thru Blender 3.1.2

.iqm : opensource skeletal format.

• iqm devkit

Tutorials / Help

Fairweather has a YouTube channel series: Modeling for Quake that covers many of the aspects of working with Blender for Quake modeling.