The first Chrome Dimension level can be unlocked from a chrome ‘egg’ found in Level 1-16. Note that the chrome egg was slightly hiding behind the 0 at one point right after zooming out (more information in the Chrome Control guide.
Getting 3 stars in this level may take a couple of tries. Use the first red bird to weaken the structure. Use the second white bird to make everything collapse. This one may take a few tries to get the right angle of. Once you hit everything, you should be able to get all 3 stars.