Is there a way to still do graffiti even if I don't buy caps?

I've been wanting to start getting into doing graffiti and I've done research on different styles and found what resonates with me. Right now I'm just wondering is it possible to just use a regular old spray can to paint without getting a different cap, or is that kinda a must have? I know that very skilled artists have done it, but is it something doable for a beginner? There's so many beautiful murals around where I live and I want to be able to start practicing and do that.