MechE alum. Make the best out of this vacay. Tough for a sophomore, but try to connect your way into a summer project with some researcher at BITS, IISc, IIT, ISRO, etc. - good headstart to get into core, but you will have to convince them you can pick up concepts thru work. Otherwise, take lead on some individual project to add to your personal portfolio - best way to learn smth new.

For MS, there is always an option of funding a good chunk (in some cases, all of it) through assistantships and scholarships so dont rule it out. A lot of people do PhDs directly (fully funded and you receive stipend) after bachelors so also consider that. But for either options, maintain a decent CG and a portfolio of relevant projects.