cat litter box.

One of my inventions was a cat litter box. This was because I had four cats. I was tired of playing dig and scoop. So, I bought 3 plastic litter boxes. I took one of then and drilled holes in the bottom of it. I created a grid of holes. Then, I put the litter in one of the litter boxes with no holes. The other one, was meant to hold the litter box with the holes in it. When it was time to change the litter (the cats would walk around with masks on their heads), I dumped the litter from the full box into the empty ones. I would pull up the litter box with the holes and shake it from side to side until no litter was left.
The residue in the litter box with the holes would be put in the trash. Now the litter is clean and in a new box. I would play this back and fourth game between the litter boxes. This was my invention in 1992. It is now possible to buy litter boxes that work this way.