I always had a hard time finding a litter box that was deep enough for my cats. They kicked loads of litter out the side with traditional boxes. Then I tried a covered box and it just made them stinky when they came out. So I made my own litter box.
By cutting the entance so big and so low, you're still allowing litter to be kicked out of the box. I suggest that you don't cut a hole at all.
I use a large file box without the lid, and pour the litter into the box. I have a 23lb male cat and he is able to jump in and out, leaving the litter inside the box.
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I have found a great idea for a hidden kitty litter box! Go to the nearest thrift store find a decent sized two drawer night stand. Take top drawer out and cut the face of the drawer off.
I love cats. But I hate the litter. They scatter it all around. Some dogs love to get into the litter.
We made this litterbox out of a $4.00 tub. We used a dremel to cut the hole, It is bigger than the normal box and easier to open and clean.
While shopping in a department store, I noticed that basic litter boxes for cats cost more than a dishpan. The litter boxes were priced at over $6.00 each. The dishpans were priced at $1.29 each.
Covered cat litter boxes are ridiculously expensive, however they certainly do help contain cat odors. Since we are a multi-cat family I found the best way to cut the cost and still reap the benefit was to use plastic storage containers.
After seeing a nifty cat box with a high price tag, I decided to make my own. It is a tote with a hole cut in the top of the lid. I had empty totes already so that didn't cost me anything.
I have a multi-cat household. After years of using covered litter boxes, which help keep litter in, but are time consuming to clean, I realized maybe a long and deep storage box would work.
This is a page about making a litter box cover. Making a cover for your kitty box may help keep the litter scatter down.