For the goal you have, the best thing to do is find something you’re passionate about and build something for it.
Ask yourself what do you love to do outside of programming? What is some problem you have that you could solve by writing a a piece of software?
You are more likely to complete a project that you are passionate about and when you speak about it in an interview your passion will show and excite the interviewer.
If there is an industry you are interested in, try to attend conventions that are relevant and go speak to the reps at the companies you are most interested in and ask questions about their products. Ask if they have any internship programs coming up and who to speak to after you’ve shown interest in their projects.
Source: an engineering manager who is not currently hiring