Just get a rectangular piece of 1/8" stainless about 10" x 15" and make your own.
People keep telling me how stupid easy it is and cheap too.
All the experts keep saying how only 316 can only be used because 304 will rot away faster than a tooth in a sugar bowl and will also attract sharks.
Press brakes are a dime a dozen, hell you can probably just go down the street to someone's garage sale and find one for $5.00.
Plasma cutters are dirt cheap too, or no wait, somebody mentioned how you can cut stainless with an oxygen/acetylene torch. I think you better try that first just to make sure it works.
Hey I know, what about going to down to your local Hertz Equipment Rentals and renting either a laser table or a water jet table? I hear those work pretty good.
If I was to want one of those square (ish) plates I think I would just do it the dumbass way and go buy one new for around $100 on sale somewhere on a website that is putting the LDS's out of business, oh wait LDS's don't carry plates because nobody wants them, never mind.
But then again I never was that bright, just look at the plate fiasco I got myself into. They were touted as the "Minimalist Marvel", they oozed minimalism out of every pore of their 304.
Oh yeah, that was a huge success!
It must have been those damn cam band slots and the fact that people couldn't put an S.T.A. on it.
Now I know what it was, not enough parts.