At heart and by training I am a mechanical engineer. I am fascinated by things that move and do stuff. For this reason I play around with making all kinds of mechanical constructions for amusement. I have a metal lathe, and metal working tools for repurposing old electric hardware. 3D printing is the ideal method of realising parts that I cannot find a suitable bit for in the pile of electrical equipment that I use for parts, and would be near impossible to manufacture using traditional tools. My website http://www.techmonkeybusiness.com has more about my projects and activities.
Well actually, the printer I use is not my own, but rather bought by my partner for her projects. I'm a bit worried that I am commandeering it for my projects. I'll just have to be nice to her to make up for it.
A word of warning: I am not a purist. My designs are very likely to include other materials and probably use tools other than a printer.
It's all fun.