You can go to a stereo shop and get a new face plate and a metal backing to hold the knobs, but usually it's used for a new type am/fm stereo cass/cd that will also have a new faceplate. The only drawback in your case is you'll see the screws you'll need to hold the new faceplate that's screwed into the old one. But I guess hot glue will work.
I had to do it for a aftermarket radio.
Mark