My cats pee is squirting out the cracks of the litter box..advice?

I made a giant litterbox from a plastic storage tub that is about 30 inches long, 18 inches tall, and I believe it's about 18 inches in width. I cut a circle 9 inches in diameter in the center of one end, about 6 inches from the bottom of the tub. The sides are solid and tall enough that urine cannot leak out of the tub when the cat stands up while urinating (unless the cat would happen to shoot urine out the door of the tub, which I've never yet seen a cat do.

Cats like the spaciousness of this homemade litter pan. I like the way it stops litter spills, urinating outside the box and poop missing the box.

You can either put the lid on the box or leave it off. Most cats prefer the lid to be off. Cats usually don't like covered boxes because covered litter pans trap odors.

Get rid of the covered box and use a storage container with high sides. This might be about 24" long x 19" wide x 10" tall. The height will help and if it is kept clean, you won't have to worry about smell.

It works for the best and worst of them.

Oh you have a covered litter pan. I suggest you get a larger and deeper litter pan and put a screen around 3 sides down into the litter pan. This way she can't pee over it and the pee would run back down IN the litter pan and not outside of it.

Get a new litter box without cracks.