Litterbox cabinet - SUCH A GOOD IDEA! Give the cats their own little litter box cubby room. It gives them their privacy and you can contain any mess on the outside of the litter box and easily clean it up.
Minimalist IKEA Cabinet Hack, and lots of other ideas on hiding a litter box. Not just for the litter box but for a dog's or cat's pet bed, when company is over or just during the day, just shut the door and it won't have to be seen until bedtime.