Infusion seems to be the way to go, but you only get one finished face with peel ply texture on the other. What's the best way to get 2 finished faces? I tried a small 150mm square by just clamping 2 peices of aluminum tooling plate together and it worked perfect with really good fiber to resin ratio, but I need some larger 500x500 plates (2mm thick). I could use 2 plates of glass backed up by something else like mdf maybe, but I imagine just clamping around the outsides is not going to squeeze the middle well enough unless I get tricky with the clamping. Maybe some thick peices that span across with clamps on outside to hopefully put enough pressure in the middle. 
Any other good way to do this other than clamping? If clamping is the best option, what's the best choice of clamping plate material and method for doing it?