Earlier I asked about double sided infused plate, which pretty much needs a core for flow, but since I'm building a prepreg oven, id like to know how it can be done this way. Let's say 2mm thick plate, and I want both surfaces looking nice. Can I simply lay the layers of prepreg on a sheet of glass, another sheet of glass on top, and bag the whole thing? If that won't work,  what other methods are there? Sounds like commercially it's done by pressing 2 metal plates together. The parts I would be cutting out of this plate are a maximum of 8 inches wide, so longer skinnier layups are an option. Maybe I could use aluminum tooling plate with reinforcement ribs going across the width. The ribs could be machined with a very slight bow to give the layup plates a slight convex, when bolting together around the outside it should give good pressure in the middle. Would this be an option as well? Curious to hear different methods
 

People underestimate how strong glass is. Theres no problem using glass as long as it is tempered glass around 10mm thick. You can simply use two pieces together and vac bag them, I do it often. Just dont drop the glass on its edge, that is where it is weak.

As for the excess resin bleed, Mat is bang on there. You need to use flash breaker tape around the outside of your laminate to prevent that.