To create nice looking, rendered (a.k.a. ray-traced) Lego models, there are three integral parts:

1. A modelling program. The free programs LeoCAD and MLCAD are both fantastic tools for this. MLCAD runs only on Windows, but LeoCAD supports Windows and Linux.
2. A Lego parts library. The LDraw system is an integral part of both the modelling and rendering of Lego creations. LDraw provides the building blocks for you to play with. It's free and updates to the LDraw system appear every once in a while. If you plan on doing a fair amount of Lego modelling, you should really keep an eye on the LDraw website for news, tips, and general Lego goodness.
3. A rendering program. The folks at the POV-Ray website have created a wonderful and powerful rendering tool. There are versions for several operating systems...and best of all, it's free! This cool tool helps us create those nice, plastic-looking, artistically lit and shaded images of Lego models.

Keep in mind that making rendered images of your Lego models need not be the sole reason for creating computerized Lego models. LeoCAD and MLCAD (combined with the LDraw system) are still perfectly good stand-alone tools. With these programs you can create step-by-step instructions of your own homemade models.

Getting everything installed so you can create your own Lego models on the computer can be a bit complicated. For this reason, I've created this step by step guide to help you get started. You will need the following files:

NOTE: You should visit the official sites as their programs may have been updated or for more information or if you are having trouble getting their programs set up.

A. Installing LDraw & LDraw Parts Libraries

1. Make a folder where you'l store all your Lego stuff (eg. C:\Lego\)
2. Throw the files ldraw027.exe, complete.exe, and lcad0201.exe into that folder (eg. C:\Lego\)
3. Go to a DOS prompt in that folder and type: ldraw027 -y
   This installs LDraw into a subdirectory of the current directory (eg. C:\Lego\LDraw)
4. Now type: complete -y
   This installs all the LDraw parts into the LDraw folder for you.

At this point you have installed the old DOS Lego modelling program known as LDraw. Both LeoCAD and MLCAD (two modern Windows Lego modelling programs) require parts information that come with LDraw. That's why we had to install LDraw and all its parts libraries. LDraw has evolved into a system rather than just a program. It is an essential part of the modelling/rendering process.

B. Installing LeoCAD

I skipped this because I already installed it once. I just moved the LeoCAD folder to C:\Lego. Just try installing it yourself somewhere under your Lego folder. If you have trouble, install MLCAD instead.

Visit LeoCAD's website for help on installing this program, though it should be pretty straightforward for most computers.

C. Installing MLCAD

1. Simply extract the mlcad211.zip file to its own folder (remember to keep the directory structure intact) within your Lego folder. (eg. C:\Lego\mlcad211)
2. Go to the folder you installed MLCAD into and run MLCAD.EXE
3. You'll be prompted for a "Base Path". Just type in the LDraw directory here (eg. C:\Lego\LDraw). If everything is okay, the Status message will say "OK!"
4. Hit the OK button and you're done! (MLCAD may, at this point, ask if you want to register the MLCAD file types. Go ahead and say OK. This just associates MLCAD data files with the program.

You are now ready to start creating Lego models!

This is where things get really complicated. You'll need the following files:

NOTE: You should visit the official sites as their programs may have been updated or for more information or if you are having trouble getting their programs set up.

A. Installing the LGEO parts library

1. 1. Unzip the lgeo.zip file into its own folder in your Lego folder (eg. C:\Lego\LGEO)

LGEO is a separate parts library. It contains very high-quality Lego parts that we'll want to use instead of the default ones created by L3P. If your model contains a part that is not in the LGEO library, L3P will generate a lower-quality one on the fly for you. NOTE: If you want to use the high-quality LGEO library, you have to make sure the "Use LGEO Library" option is checked off on the L3PAO program, which we'll install next.

B. Installing POV-Ray

1. Run povwin3.exe
2. Install the program wherever you want (I chose C:\Lego\POV-Ray for Windows v3.1)
3. Run the POV-Ray program.
4. Go to the "Render" menu and select "Edit Settings/Render"
5. Type the following into the "Command Line Options": +LC:\Lego\LGEO (This should be C:\Lego\LGEO should
be where you extracted the LGEO files.)
6. Click the "Set but don't Render" button. POV-Ray now knows where the high-quality LGEO Lego pieces are.
7. Exit the program.

POV-Ray is a free program that will render you Lego models using a technique known as "ray-tracing". You can do all kinds of neat things like set the lighting and camera angles and create high-quality images of your Lego model.

C. Installing L3P

1. 1. Extract l3p.zip into the LDraw directory (eg. C:\Lego\LDraw)

L3P is a DOS program that converts LDraw models (MLCAD and LeoCAD can both save models in the LDraw model format) to POV-Ray models. POV-Ray is the raytracing program you'll use to actually render the model.

D. Installing L3PAO

1. Extract the setup files contained within L3PAO.zip into a temporary folder somewhere.
2. Run Setup.exe
3. Install the program where ever you want. I chose to install it in C:\Lego\L3PAO.
4. When the installation is done, run the L3PAO program.
5. When prompted, select the folder you put the L3P.exe program into (eg. C:\Lego\LDraw)
6. When prompted, select the folder that contains the LEdit.exe program (this is installed as part of LDraw)
(eg. C:\Lego\LDraw). NOTE: I had some trouble selecting the proper folder as it seemed to not find the file the first three or four times I tried selecting the proper folder, even though the file was there. Eventually it worked. If it doesn't accept your answer the first time, keep trying.
7. Now go to the "Tools" menu and select "Locate LGEO Library".
8. Enter the path to the LGEO library (eg. C:\Lego\LGEO)

L3PAO is a graphical front end to the L3P program and is much easier to use.

With all that out of the way, you can now render your own Lego models you created in LeoCAD or MLCAD.

I assume you can figure out how to make your own models with MLCAD or LeoCAD. They're both pretty easy to use and have help files. Rendering is a bit more complex, so let's go over an example.

1. Run the L3PAO program.
2. In the upper-left part of the window, click on the button marked with ellipses (...) beside the drop-down list under the words "Model Files". Let's select an example model from LDraw. Go to C:\Lego\LDraw\MODELS and select CAR.DAT.
3. (OPTIONAL) Select the "Use LGEO Library" if you want a really high-quality result. Be forewarned, however, that this will slow down POV-Ray's rendering speed.
4. Hit the "Run L3P" button in the lower-right corner of the program. This will convert the DAT (LDraw) file into a POV (POV-Ray) file, then open the POV file in POV-Ray for you.
5. Once in POV-Ray, click on the "Run" button on the toolbar to render the image. Voila! A cool, 3D rendered image of a Lego model!

By default it may render the image very small. You can change the size of the rendered image by using the drop-down list on the POV-Ray toolbar. You can choose from all sorts of sizes. The sizes with "No AA" beside them will render quicker because no antialiasing is done to the rendered image. The sizes with "AA 0.3" will be antialiased. Antialiasing is when you add extra colors around diagonal edges to make them look smoother. They'll look a lot better, but will take longer to render. Be warned that large images can take minutes to render! Also, the complexity of the model can slow down rendering immensely.

Well, I hope these instructions were easy enough to follow. Have fun creating your own Lego models on the computer!