Hello!

Apart from Aerospace and Aeronautics, You will have scope for designing Drones, Machine guns, Missiles and other military equipments if you take courses like B.Tech in Mechanical, Nuclear, computer science, Electrical, etc.

After you have completed your Engineering, you can join the Defence forces as well where they will train you specifically in these subjects.

You can even look into the Ordnance Factory Board, It is the world's largest government-operated production organization and the oldest organization run by the Government of India for the production of military weapons and ammunition. You will need to clear UPSC examination in order to get into it.

Hope this helps!