Ive got a 30cm x 30cm square metal baseboard, covered in airtight foam, with a hole drilled in the middle which is connected to a vacuum pump that id bought from carbon mods.  If i place any jar over the middle and turn the vacuum pump on the pressure pulls the jar into the foam creating an airtight seal.  The beauty of this system is you can change the size of belljar to suit your job, a coffee jar is good for degassing and I use a big clear plastic tube for larger jobs.