I have used litter boxes with and without a grate. When we had a box without a grate, we put a thin layer of hay across as MD suggested, and that worked well at keeping things clean and together. But I have also found a really great system for a box with a grate. A few years ago I bought a “large” rabbit cage (a living room one on wheels) that has a grate in it. We added a hay box at one end and their bowls at the other. The nice thing about this is that it keeps all the mess and accidents inside, so all you have to do is clean up one box and that’s it. To help the pan last longer (this cage isn’t cheap I have to admit) we cut open 13 gallon trash bags to use as a liner. Every other day we pull the pan out, pick up the bag, and drop it in the trash. Occasionally some liquids can get under the liner, but there isn’t any litter to cake the urine onto the pan with, so we are no where near needing to replace it. We also added an exercise pen by clipping it to either side of the cage for when we need to keep them contained.