[X4U] Flush OS X memory?

[nk]

I need to open an illustration for a client to show them what I have  
so far, but I'm unable to get a preview (Illustrator) because there's  
not enough free RAM, and I think THAT is because something in the  
system isn't "letting go."

I've quit all the apps I can (3D process ongoing for another client),  
and still can't get a preview.

Is there a method or a freeware doo-dad which will free up RAM?

Since I created this illustration on this very computer, I know  
there's enough memory to work with and preview it. I think the 3D  
work, which I have shut down on this partic machine may be the thing  
"unwilling" to release RAM it had been using.

thanks!

n