The corner brackets in the basket model I have are cast from iron and very weak (think cheese metal). You can't buy the brackets as far as I know so the choice was to discard the frame and baskets or print a replacement.
It's a very basic print, printed on its side for strength. I emulate the original as closely as possible including the raised retainer but decided to skip the raised lip (which would be a nice aesthetic improvement).
I printed it in PLA since this is all I have, it's strong enough and has been in use for over a month without issues.