So, I'm planning some FF kitchen cabinets and don't know if I'm thinking the process correctly. I have a row of uppers that will have different height of cabinets, imagine cabinets over the stove combined with regular height cabinets, for example. Now, I'm thinking that 3 separate cabinets will need to be built, then the FF's attached to each other during the mounting on the wall.

My question, since the FF extends slightly past the edge of the actually box, there will be a visible gab between each cabinet as viewed from underneath. I was planning on mounting some type of thin material to the bottom of the uppers to hide the gaps. What do you guys think, or how do you handle this?

Thanks.