I bought a prefab teak grate from camping world. I don't remember the brand, but it is a common item.
It was 35 or so bucks last year.. no doubt it is more now.
It fits perfectly lengthwise in my
Burro bath, but is an inch or so shy in width. Not that big a deal for me.
It is always clean, and I lift it every once in awhile to clean the floor under it.