miniproject for 3rd mechanical students

You will have to search it yourself. There are so many things in the world. You can even research something eg. technique to increase the efficiency of the Brayton Cycle or something in Robotics to name a few. First decide what you are interested in and then do a project on that specialization of your branch. Decide a project, start working on it, you will face some problems, many you will be able to solve yourself, those that you can't....ask those questions here and someone or the other will be more than happy to answer your queries.
Best of luck for your project👍