Mechanical Design for a Newbie - How-tos? Tutorials? Books?

All - I posted something along this line here:,124305.msg937615.html#msg937615

...but it's become buried, and since it was off-topic anyhow, I decided I would post the question here, to see if I get any responses.

So - my question(s):

How do you learn to do mechanical design of devices? That is, how do you go about learning where to position what and size things so that in the end, it would all come together and fit right?

I see projects like custom cases, or laser-cut hexapods, or custom 3D printed cat feeders (you know who I'm talking about) - and I wonder: How do they do this?

The same comes to mind when I see commercially made products - printers, cell phones, cars - you name it: From a simple snap-together container to a complex engine...

I know this is all mechanical design and such, but how do you go from being a mostly "newbie" to being able to make such a design? Are there books available on it? Online tutorials or courses? Any thing else?

A long time ago (junior and high school), I took a few drafting classes that taught how to do technical drawing (pencil, paper, t-squares, etc), but there wasn't much emphasis on how to design something from scratch. I understand that you need measurements, layout, tolerances, etc...but not much else do I understand.

Furthermore, what is needed to say - use Blender to design a gear train with the proper dimensions then print the pieces out using a Makerbot Replicator (or similar 3D printing device - or a CNC machine, or a laser cutter, etc)? It seems like all I can find out there for such work is "how to design things" but they don't go into the deeper knowledge of how to lay out holes, etc - and know how to know it fits together properly, etc - then how to split it up into parts for "printing"...

So - where are these tutorials? Where and how do people learn this kind of thing (if they haven't gone to school for it - and can't go now due to any number of reasons; in my case, time and money limitations)?