I was introduced to 3D art and 3D modeling by my brother when I was twelve years old and have been doing it for a hobby (and hopefully future career) for nearly six years. I started out with Google Sketchup, then moved to Autodesk Maya 7.8(?) Personal Learning Edition, and now I have settled with Blender, which I've been using for maybe three or four years. It's free (necessary at a young age when your parents aren't willing to pay thousands of dollars for a mere computer program) and still allows me to do just about anything that the industry bigshots like Autodesk 3DS Max, Autodesk Maya, etc. can do. If Blender's Cycles renderer can't suffice for something, I use an external renderer called LuxRender.
Everything I've learned has been self-taught for the most part (based on research and tutorials), with some tips and tricks from fellow Blender artists.
So far I'm terrible at human/animal anatomy, and I've yet to figure out vehicles. For the most part I specialize in weapons, most commonly firearms. I equate cars to anatomy. I just can't wrap my head around the process of recreating their shape. Furniture and appliances aren't very difficult, though.
I'm willing to dabble in designing anything I can think of or anything asked of me, provided it's something I can create in a 3D modeling program (as explained previously). I'll do jewelry, weapons, furniture, clothing, vehicles (depending on the vehicle), cakes (yes, the food, such as wedding/birthday cakes), caskets and gravestones (yes, I'm willing to design a person's casket or gravestone, as morbid as it may sound) and other things. Just ask and I'll tell you if I can create it or not.
To those who wonder why I do 3D art, I enjoy it because it allows me to have full control of the environment and final output. I'm able to create anything I please -- be it real, fictitious, or concepted (by myself or others) -- and I don't have to spend tons of money on professional photography equipment or tools and raw materials. Best of all, I can make it look real.
To those who'd ask "Well why not just be a photographer so you don't have to hand-make everything?", it's a pain to have to rebuild some part of the world from scratch (create and tweak materials, set up lights, build whole scenes/objects/environments by hand), but it's what my resources and talents allow for, and I personally think that there's more skill involved because one has to really pay attention to how things look and how they interact with light and so on. Of course, painters and such have to do this to an even higher degree, but my 2D abilities didn't develop nearly as much as my 3D abilities did and I don't have the discipline to go THAT far with rebuilding the world.
I make all my deviations printable, should anyone decide they like something enough to get a print of it (every bit of money helps nowadays) and stick it on their wall or something. Feel free to send me a message if you want to request a different size of one of my deviations (or you want something to have a different color or some such) and I'll try to have it released in a timely fashion. After three years of inactive deviantART membership, I've started making more upload-worthy art, so I'll be more likely to use and follow this site now.