A friend is making a cabinet, has fastened the back and the dividers to the
base, and finds that the dividers stand about 1/8" taller than the back.
What's the best way to bring the dividers down flush with the back? His
tool selection is very limited (he's making the cabinet parts with a
circular saw and a straight edge). The material is 3/4" plywood with a
paper-thin black walnut veneer.

No, this isn't me. I would have solved the problem before I fastened the
dividers in place.

Thanks for the help.

Lionel