Qualifications
If you just want to be a mechanical engineer, you'll first need a bachelor's degree in mechanical engineering or mechanical engineering technology. If you want to be able to add research to your job description, especially in order to innovate on other designs, you should get some grad school under your belt.
In addition, you'll need to be licensed, which is a fairly time-consuming process. To even be able to take that exam, you'll need a degree from an ABET-accredited program and four years of relevant work experience.
It's no walk in the park, but fortunately you can break the exam up into two parts. The first comes after you graduate and become an Engineer-In-Training (EIT) and the second will be after you've gained the necessary experience as an EIT. But then you're done, right?
Well...maybe. You may need to renew your license again (and again and again and again) depending on what state you live in (source).