[CeciL]

Try swimming. It will broaden your shoulders and chest without weights.

However, if want to get "buff" weights are it. Preferably free weights, they work your balance muscles as well as your target muscles so you get useful strength instead of just bulk as gym equipment tends to do as the exercise is too focused. Try some heavy music and you will be slamming those weights around in no time and don't forget to eat a lot of protein.