Custom-made litter box?

Anyone know where I can get a custom made stainless steel sifting litter box? All the ones online are not big enough (biggest I could find ANYWHERE was 23x15 inches). All of the other things like using a storage container or makeshift steel bin don't have the sifter.

I use pine pellets and I'd like for it to be at least 30-35 inches long x 20-25 inches wide. Both of my cats have a habit of stepping in their poop and only seem to avoid it regularly when they have a big enough space. I'm willing to pay a good amount. Don't want plastic for hygienic reasons. If anyone has any ideas on how to do this DIY please let me know!