Making dies for the press

What size of plates fit into the press? Im planning on making some set at 45degree angle so we can metal perpendicular or parallel with the dies. Would that cause any issues?

The die plates are 4"x8" and I believe it is 1/4 material. I want to build some dies myself. I don’t believe what you want to make will cause any problems. I have some dies I’d like to make, too.