I want so bad to be able to do this. How does one get started in 3D printing? I understand how Shape ways works, but it is the computer design aspect that has me baffled.
I agree with Peteski's thoughts on getting started. There are some terrific software tools on the market now and the learing curve to get started is so much smoother than it has been in the past.
To get started, try a really intuitive tool like SketchUp. The first challenges are largely around developing a sense of how to best represent something real as a 3D drawing and becoming familiar with how the tool itself wants to work. This is where the ease of use that is such a hallmark of SketchUp really makes it a worthwhile place to start. If you're completely new to 3D drawing, there are a lot of great tutorials on how to use SketchUp and how to force it to do just about anything. Instead of making it hard on yourself, for a first drawing maybe start with something like the computer desk you're sitting at and try drawing it in 3D. Then draw the outline of the room you're sitting in. All of these skills build on each other and do all of this in full scale. When it comes to developing model railway parts, I tend to liken the design work to how I'd approach it if it were a traditional scratchbuilding project. We're just scratchbuilding and kitbashing using digital styrene, wood, and brass.
The desire is the hard bit so you're well on your way. Don't hesitate to post any questions - I know I'm not alone in a willingness to offer help when you get stuck. We're really all in this together.
/chris