how do i generate clouds on a skybox

hello I was wonder if it's possible to generate clouds onto a skybox then have that sky box rotate to simulate cloud movement, and if so how would I do this. I don't really have money to pay for things like unisky this is why I'm asking. thanks for your help.

Have you tried creating a plane just below the sky with a large texture and scrolling it's offsets or did you want volumetric clouds?