This is my free poster mockup. It is 3d render based with realistic light. You can easily customize it and use it in your commercial and private projects.
Use Smart Ojbect to replace default poster design to your own. It is standard European B1 poster size.
You can also change wall, floor and passe-partout color. If you don't want to use default color simply make those layers visible and change their shape color to match your design.
I have added lamp and chair objects to fill the space around poster but I didn't want to distract the viewer from poster itself so I left them without any color and details.
Render passes work best in 32 Bit linear mode. The only thing you need to do before you save in your favourite format is to change mode to 8 Bits/Channel and merge the document when your work is done.