Just got ahold of an old Stanley No. 8. Was looking into how to get it up to shape and I'm not sure what to do about flatting the sole. I know most situations can use a sheet of glass or a granite slab. But with the sole being 24 inches long, and the world on lockdown because of COVID I was wondering if anyone has any other easy to find flat surface solutions out there? I hear that a No. 8 doesn't have to be SUPER flat so I was thinking possibly a length of shelf melamine might be useable, but im afraid of there being any bend in it.

Thoughts?