Trim the Backsplash With Snips
A router won’t be able to reach the inside corner of the backsplash, so use tin snips to trim it down before you install it (make small cuts). That way you won’t have as much material to remove with your file. Press the section on with a board the same way you did the top. The top cap piece is set into place with a hammer.
Trim Out the Sink Hole
Use your router to trim the hole for the sink. Just poke through the material with a spinning bit and work your way to the edge. Right before you finish the cut, support the scrap material so it doesn’t fall down and tear out the last little section.
Once all the pieces are in place, file all the edges, including the bottom. You can buy a file especially designed for plastic laminate for less than $20 online. Always file in a downward direction, never back and forth. Clean off excess glue with lacquer thinner or whatever solvent your adhesive manufacturer recommends.