Machining is an excellent skill and hobby; whether you crank handwheels or watch a CNC system sling hundreds of pounds of iron around, it is a fun and practical way of realizing your ideas. Many people now prefer to use other fabrication methods like 3D printers and laser cutters, but machine tools can produce parts with much greater precision and better finish.
In addition to machining parts for various projects, I've made some standalone pieces in a machine shop, documented here:
aluminum rubik's cube - 2006
A fully functional Rubik's cube in 6061 aluminum.
stainless steel rubik's cube - 2012
Another cube, this time in manually-machined stainless steel.
alumine avian - 2013
A sharp-looking stylized bird sculpture.
sound-tron: experimental whistle - 2009
An unusual magnetron-inspired whistle.
medallion - 2012
A decorative medallion for a messenger bag.
grading stamps - 2011
Grading stamps for CMU's operating systems class.