Today at work we had a demo of the RTM process (resin transfer molding) for composite fabrication. This is dry carbon fiber layed up in the demo mold, which I helped do. After this several layers of stuff are added to help the resin flow better and to make the part easier to remove, and then a vacuum bag is placed over the whole thing and stuck down to the yellow putty on the edges. Vacuum is pulled, the valve to the resin tube is opened, and the part fills. More or less - it didn't quite go as planned with this particular part, but we learned a lot.