That might have been me.  I have two large cats, and no room for a
second box.  

I use a mortar-mixing tray from Home Depot, which is 26" x 19" and
6" deep, and very sturdy plastic like a litterbox.  I think it cost
about five dollars.

The sides slope out from the bottom, which solved the problem of
one cat backing up to the end or corner of the box, and managing to
pee over the edge half the time.  Before, I had a litterbox inside a
plastic storage bin, but it was very messy to clean up the escaped
urine in the outer box (storage bins aren't made sturdy enough any
more to use by themselves for long).  With the angle of the sides of
the mortar tray, he can back his feet up to the edge and still pee
inside the box.

--
 jamie  (jamiemck@newsguy.com)

         "There's a seeker born every minute."