We stopped making framed lithos at work ("motivational" posters). I was allowed to take home the remaining frames. These are unassembled, and the two precut sizes are 22" and 28."
That means you could make 22" or 28" square, or 22"x28" frames. The material is anodized aluminum with mild steel corner locks.
If the Otherpower forum store owners want the lot I have to offer, I'll be glad to donate them. There are enough pieces to make over 100 frames.
I don't want to sell/give them away 1 at a time. You can go to any Wally World or Dollar Store and buy a framed litho if you want one.