A machinist is a person who uses a machine to build, repair or modify tools and devices. He mostly works with metals, since most of the things you see in day to day life are probably made of metal or were made with a metal tool. Aside from metal though, machinists also work with different materials - most notably wood and plastic.
The nature of the work can be quite broad. It can be as simple as working on small projects like making solder joints to make small metal trinkets, but it can be as complicated as working with industrial-sized vats that need repairs or extra tweaking. It can also include working on rebuilding or repairing automobile parts that are made of metal. A machinist is an expert in materials and machines - he must be familiar with the proper and effective use of tools like a soldering iron, chain saw, drill and the like, as well as knowing the melting and boiling point of certain metals.
If you have sufficient visual intelligence and spatial intelligence, and a love for building things, this might be the correct career path for you. The job requires you to think in three dimensional shapes and figures and to conceptualize these very shapes as well.
Basic knowledge. A career in machines starts early in high school. The subject that a machinist would probably enjoy the most is trigonometry. This is because it involves shapes and spatial computations. To sharpen the mind, basic engineering subjects like drafting can also be taken as elective or higher learning. If the school offers subjects in the practical arts, the student can also learn the basics of welding, soldering and the use of other power tools and heavy equipment. This will come in handy for his future job as a machinist.
Apprenticeship. Machinists can go straight into the job after graduation. Just like most skill-based occupations, the easiest and best way to learn the tricks of the trade is to learn on the job. This usually works through an informal apprenticeship system, wherein the younger and newer machinists are paired with older and more experienced machinists. This helps makes learning processes easily demonstrated, since the student can easily see the correct way of doing things, while the more experienced teacher can easily correct what the student is doing right there and then.
Vocational courses. If you don't want to go to work yet, you can study at a local college that offers vocational courses. These are short courses of from a few weeks to two years that help students grasp a particular set of skills. This also commonly comes with hours' worth of on-the-job training at an affiliate workshop or institution.
Certification. Certification is also available for those who want to go for higher-profile jobs. The National Institution for Metalworking Skills (NIMS) and the local State Apprenticeship board usually hold examinations to certify machinists. This allows machinists to become more specialized and officially make their specialized skill known to their employers.
There are many routes to being a machinist, so if you're into problem solving and can work a power tool really well, this would be a good start.