We recently put a new Allure vinyl plank floor in our kitchen and the installers put in 3/4 round along the baseboard. Now our standard louvered register covers will not fit unless we push part of them under the 3/4 round. I found some Toe Space Grilles today... totally flat so I could move them (and install with screws) where I wanted without having to hit the 3/4 round... unfortunately I am not finding them in a size that will cover the 4x10 vent hole.

Is there anything else that is perfectly flat on the bottom that would serve as a grill and could be screwed in place? I've seen the decorative iron grates that look they they would work (if they do not have a 'lip' on the bottom)... but they are very expensive.

Ideas?
TIA