I study chemical engineering, and a big part of what we do is develop reactors that produce high-value materials like plastics from starting materials such as oil and biorenewable resources. Since a lot of what I do is very new and not well understood, I make small-scale models of a process, test it to find a chemical reaction system that works, and then work with other scientists and engineers to "scale up" the system until it is a true industrial process. In this reactor, for example, I am working with a team of scientists to make nylon plastics from biorenewable resources.
Here is one of the reactor controls, where I control the system's pressure. Typically, student researchers design and build everything that they use.