not aware of anyone who makes one, and your posters would get damaged by handling unless you plan on using a hard cardboard behind it. Not practical
I might also add I have made such a beast from one sheet bags for convention display
they only were good for the small sizes and the posters regularly got folded back, dinged and all the rest of the maladies of paper handling
I'm looking into getting a huge shrink wrap machine and hundreds of sheets of foamcore.. expensive consideration
