i made a new cabin without flat walls, so i needed picture frames to hang posters properly in it. figured i might as well share them. you'll need to use manual positioning mode to fit your posters behind the glass, but then they'll be nice and protected.
also, it seems like images uploaded as posters will always be rescaled to 1x1 proportions initially, so be aware of that and maybe add transparent space around your image to make it fit that resolution scale for easier scaling and placement.