So, you're a stubborn Maya User and have a masochistic desire to create your models without having to touch XSI or Max.  I can completely understand not wanting to touch 3D Studio Max.  You're in a safe place here.  Assuming you have already looked all around to find a decent tutorial for creating a prop from scratch using Maya, I'm guessing that you didn't find anything adequate yet.  The best example out there currently is Palmer's Maya Prop Exporting Tutorial, which is a great resource, but still only covers the guidelines for exporting your mesh.  It does not cover UV Mapping or things of that nature, which is why I decided to write this tutorial.  The aim is to create a prop from the ground up, and by the end of this tutorial you should have little problem creating your own Maya physics props.

Also, this tutorial will teach you have to export your models using both Prall's exporter scripts and Valve's own SMD exporter plugin for Maya.  It's like having a threesome only it's not something to brag to your friends about.

Step 1 - Getting Started & What You Need

This tutorial uses the following software and tools to create a Source model:

• Alias Maya (version 4 to version 7.5) or Autodesk Maya (version 8 to Maya 2008)
• Prall's Half-Life 2 Exporter v2.5 for Maya, the collection of scripts required to import or export SMD files in Maya. OR you can use Valve's SMD Exporter.
• Valve Source SDK (Installed through Steam)
• Adobe Photoshop or any other program capable of creating textures and saving them in Targa (.TGA) format.
• NVIDIA Adobe Photoshop DDS Plug-in, optional unless you wish to create normal maps for the texture that goes on your model.
• GUI StudioMDL (a GUI frontend for studiomdl.exe used to compile the models)
• Source MDL Texture Info, a program that will help debug texture info about a model should you run into problems.  Not required for the tutorial, but recommended.
• A text editor of some sort.  I use TextPad.

Installing Prall's Half-Life 2 Exporter

Some of you might already have noticed that the latest (and final) version of this already comes installed with the Source SDK in the %sourcesdk%\maya\7.0 directory (%sourcesdk% is a Windows environment variable to points to the Source SDK installation directory, usually something like C:\Program Files\Steam\steamapps\<steam username>\sourcesdk\).  The exporter itself is not an executable program or a Maya plug-in library (.mll file), but a collection scripts written in MEL (Maya's embedded scripting language). 

Installing this collection of scripts is very easy.  All you have to do is select all of the files and folders inside the %sourcesdk\maya\7.0 directory and copy them over to the following directory:

• Windows XP: C:\Documents and Settings\<your username>\My Documents\maya\<current version number>\
• Windows Vista: C:\Users\<your username>\Documents\maya\<current version number>\

The directories should already be created by your Maya installation.  Copying these files over won't overwrite anything important, so don't worry about saying "Yes to All" if you get some warnings saying that directoryes like prefs\ already exist.  If you have Maya already open, you should close it and restart it, and you will see that in the File menu a bunch of options have shown up giving you the option to import/export SMDs.

Installing Valve's SMD Importer/Exporter

Valve recently (re?)wrote their own SMD importer/exporter.  The advantage of Valve's Importer/Exporter is that it uses a Maya Library (.mll file) to do the SMD file I/O operations, thus logically speeding up the process of opening or saving a .SMD file since it was written in a lower level language (C++).  Logic dictates that, because despite the fact that Maya relies heavily on MEL to function I doubt that file I/O is one of those things.

Rather than have you copy files over (by the way, Valve's importer/exporter is in %soucesdk%/maya/7.0/modules), they've set you up with a nice .bat file to click on that will automatically do some background work (setting environmental variables) for you and then load up Maya.  To enable the SMD I/O library plug-in in Maya, click on Window→Settings/Preferences→Plug-in Manager in the menu and a dialog box should appear listing out the various registered plug-ins.  Under the loaded column check the box for vstSmdIO.mll.  And that's it!