Is the phrase "make waves" used with the sense "create a snowball effect"?

"Make waves" is a well-known English idiom, and it can have several meanings, but I don't think it fits the described context:

make waves: to cause problems by making suggestions or criticisms

(Macmillan English Dictionary)

makes waves: to disturb the status quo

(Webster's Unabridged)

make waves: create a significant impression

he has already made waves as a sculptor

(Oxford Dictionaries)

UPDATE: At the moment I cannot think of a suitable idiom for your intended meaning. I think Edwin's "ripple effect" captures one aspect of it, but I'm not sure "let's create a ripple effect" sounds like a good motivational line, which seems to be important.

You mentioned the end result of the open-source community effort would be "something big" (i.e. a popular, successful open source project or initiative.)

Let me suggest a different water-related idiom that basically means "make famous" or "attract attention": make a splash.

attract a great deal of attention

(Oxford Dictionary)

Take a look at the open source rookies that made a splash in the past year

(infoworld.com)

If this fits your purpose, you could end the post with "Let's make a splash together!"

Perhaps you've got [have] a ripple effect at the back of your mind!

a ripple effect

if something has a ripple effect, it affects something else, which then affects other things

Court rulings often have a ripple effect, spreading into areas of law that weren't part of the original cases.

Cambridge Idioms Dictionary

You'd want 'Let's create / produce a ripple effect!'

Waves only amplify when you apply them at a resonant frequency. Snowballs get bigger no matter which snowy hill you roll them down.