As a cat owner, I'm surprised that they don't already mass-produce a product like this. Everyone who owns cats knows about the problem of litter kicked out of regular cat boxes and tracked around on cat paws. I put expensive litter mats in front of my regular covered cat boxes, but my cats just jump right over them. By putting their pan inside of a larger box, with the exit up high, where litter can't get kicked out, and by providing the sisal ramp to clean the cat's paws, my floor stays spotless.
Hot Cutting Tool (or hacksaw or other plastic cutting device)
Electric Screw Driver
Square or Straightedge
1x Regular Cat Litter Box
1x Plastic Deck Box
1x 1" x 6" board (actual width will depend on the hole you cut)
2x Metal L-brackets
4x 1/2" screws
100ft Natural Sisal Rope (1/4" thickness)
1x bottle Carpenter's Wood Glue (fast drying 30min)
1x roll of Plastic Tape
Step 1: Make a hole.
Use a Hot Cutting Tool (or hacksaw or other plastic cutting device) to cut out the opening. If you use a hot tool, do the cutting outdoors because there will be strong fumes. If you cut using a saw, make sure to file or otherwise round the edges so the plastic is not sharp.