How can I get some colour in my hair without resorting to dyes or extensions?

I like my hair the way it is – black, wavy-ish, but I’m thinking of spicing it up a little. And I don’t have any problems with getting a drastic hairdo… However, I am currently hooked with the idea of getting dreadlocks and threading it with colour… I think I’d like those kind of locks, but not really sure if I have the dedication to actually finish the job (Yup, total DIY). And I’m not exactly sure how to clean threaded dreads. So, should I or should I not? And I’d love to hear any alternatives you have in mind. No mention of hair dyeing or extensions please.