A VRML world consists of a bunch of objects. While you certainly could type in the VRML code for every object, and many people have, you save time and effort when you use a tool, called a world builder or modeler, to generate and position the objects in your world.
There are three basic kinds of modelers you can use to build VRML worlds:
An integrated modeler will let you do at least some of the following:
Of course there are lots of ways a modeler could implement each of those functions. To animate an object, the modeler could let you drag and drop a behavior from a menu onto the object, or it could have a keyframe editor that gives you fine control over each step of the animation, or it could simply not support animation and require you to read the spec and figure out how to do the animation after you're finished modeling.
Integrated modelers for the PC include such products as Spazz3D, Community Place Conductor, AC3D, VRCreator, VRealm Builder, Beyond3D, and Cosmo Worlds. The modelers are in roughly ascending order of price today, from free (beta) to US$999 (list price), and are by no means the only modelers out there.
Most of these modelers will have a demo version you can try to see how the tools fit with your creative style. If you find one you love and you can afford the price, stop right there and buy it. Your search is over.
Most folks aren't so lucky. One version of one of these modeling programs had a teensy little ElevationGrid editor that I found much too hard to use. Another assumes that every color you put into the world is going to have the same shininess and the same specular color as every other. In a number of these modelers, the programmers have seemingly never heard of anyone who wanted to add or take away points from an object. But most of the time these modelers and others I haven't mentioned are terrific tools that will let you think about creating objects instead of plugging in numbers.
Just about every CAD program exports VRML. Some still only export VRML 1.0, but that's easily curable with a VRML 1 to 2 converter. Other CAD programs have no animation, or else can't export their animations to VRML. With those programs, you may want to create the objects in the CAD program and then import them into a VRML modeler to finish your work. Still others will only generate a subset of the possible VRML nodes. For example, you could put a sphere in your scene, and the modeler will export the IndexedFaceSet that's the equivalent to the world. I advise using those modelers only to generate the kinds of objects that are hard to generate in your VRML modeler. Others can't export color. I advise using those programs very early in your process.
Note that we've already arrived at a partial solution for what to do if you like the way a VRML modeler does some things, but hate the way it does others. The combination of a CAD modeler, particularly if you already have one or can get one cheaply, and a VRML modeler can be a lot more powerful than some VRML modelers by themselves.
Some modelers such as Breeze Designer, LightWave, 3D Studio Max, DesignWorkshop for Mac, and TrueSpace, are designed for other environments, such as raytracing and 3D animation for movies, but they also export VRML. A lot of VRML worlds were built with these modelers because the state of the art of VRML modelers was pretty bad. Nowadays VRML modelers are so much better that just about the only people who use a different kind of modeling program to export VRML are the people who already have that program and have got so good at working it that they don't want to bother to learn another.
Nendo is a single-function tool for building 3D objects from scratch. That's all it does, but if you like the way it does things, you'll think every other object builder is crude and limited. Leveller and Terrain Forge are single-function tools for building terrains. FORM and Lparser focus on generating objects from mathematical models that look eerily alive. GLView is a VRML browser that also has some nice tools that make setting colors, lights, and viewpoints a snap. Spazz3D (an integrated VRML modeler) has some wizards and extra features that some people find so handy that you might think about getting it even if you've already decided on another integrated VRML modeler.
So now we have another solution. If I hate the object creation tool in VRML modeler X, I can build my models in Nendo or TrueSpace. If I hate the ElevationGrid tool in VRML modeler Y, I can use Leveller or Terrain Forge to build my terrains and do everything else in my VRML modeler. If VRML modeler Z doesn't give me the colors I want, I can run it through GLView to give the colors a final tweak.
The point is to find the combination of tools that works best for you, so that building VRML worlds is fun and productive. Unlike the situation a year or so ago, when you pretty much put up with the limitations of the tools that were available and spent half your time cursing, there really are enough choices out there now that a few minutes researching and perhaps a few dollars spent will let you put together a toolkit you'll enjoy using.
You want free? We got free:
The VRML Repository maintains a pretty good sized list of geometry modelers. ZDNet also has a list of VRML products (alas, not separated very well). ZDNet did some reviews of VRML modelers that might be useful. Don't forget the POVRay site (under Links and Resources).
You might want to check our pages on tools and converters to fill up your toolchest.
But for goodness sakes, don't do what I did. I was writing an article on VRML modelers, so I installed six
modelers and tried to do the same moderately simple task on each of them. By the time I was done, I was so sick
of modelers that I scratched all but one of them off my hard drive and didn't look at another modeler for two years.
Take your time and don't try to come up with the perfect toolchest all at once. You'll find some tools that
can turn you from a world visitor into a world builder.
Did I leave anything out about object modeling that you need to know? Let me know.