Something like this:

Apparently, these were a semi-standard size back in the early '70s, but almost everything made today has a 24" depth opening. I called at least a half-dozen suppliers, and all have only bond tins for a 24" depth. I did get a quote for a custom size from one of the companies, but the price is extremely high per box. While that is an option, it does not feel like the best option.
Thanks,
Blue