I used a belt sander and a few hand files to fit each of the steel pieces.
The second piece was a little more difficult ot fit than the first because of the narrow piece on the lower end and the curved part.
The third piece took quite a bit more work than the first two. At first I used magnets to hold in place while checking for fit.
As I got it closer I switched to Cleco's to hold it in place while I bent the curved part to fit.
The fourth piece was pretty easy.