The Vacuum Storage Bags i mentioned have a seal on one end, just looked at mine and it's 900x1200. I did post a picture on the forum for someone that was asking what type of glue to use in veneering that showed the setup i was using, unfortunately i lost all my photo's and 4 years of other stuff when i had a PC incident but it should be still on the forum, search veneering and see if it comes up, the job i was doing was flat and it came out fine(was a proof of concept thingy), if you find it you will see some blue material in the bag and some white tubing, the blue stuff is a plastic mesh and the white is spiral cut tube (stuff for tidying wires), think maplin was cheaper than the composite site. this just ensures the vacuum reaches all parts of the surface as i was concerned that the bag would just suck down locally @ the vacuum inlet.
Hope that helps
regards
Mike