A dog crate tray is around 1" deep which is no good for containing litter or hay and can leave a lot of mess outside the crate. To solve this issue you can create a frame around the base of the crate using wooden skirting, Perspex or corrugated plastic (e.g. Correx). A deep tray (e.g. a storage box) containing any litter and bedding is another way to reduce the mess.
Jazz up a dog crate. Plastikote spray paint is a great product to use to put some life back into old, worn pet cages. I acquired this crate for £10, it was rusty and very used. Sanded it down and sprayed. Going to add lino to the bottom tray and will be a fantastic base for my bunnies room!